feat(ui): External-Agent-API + Besitzübertragung UI (UI-Backlog Module 15+16/16)

Modul 15 External-Agent (ai_assistant-Plugin, Manifest settings_page):
- SettingsExternalAgents.tsx: Agentenliste mit curl-Snippets (run/status/stream),
  Copy-Buttons, Bearer-Token-Hinweis, Rate-Limit-Doku, Token-Link
- api/externalAgent.ts (useAiAgents, buildCurlSnippets, curlCommand)
- Manifest: settings_pages +external-agents (order 61, permission ai:read)
- Komponenten-Map regeneriert (43)

Modul 16 Ownership-Transfer (Core):
- SettingsOwnership.tsx: Admin-Gate, From/To-User-Selects, 10 Entity-Type-Chips,
  ConfirmDialog, Ergebnis-Tabelle
- api/ownership.ts (useTransferOwnership, OWNERSHIP_ENTITY_TYPES)
- Route /settings/ownership + Nav-Eintrag

i18n de/en +28 Keys. Vitest 12/12, tsc 0, Build OK, ruff OK, Manifest-Import OK

frontend/src/pages/Settings.tsx

@@ -53,6 +53,7 @@ export function SettingsPage() {
     { to: '/settings/permission-templates', label: 'Berechtigungs-Vorlagen', icon: '\ud83d\udd11' },
     { to: '/settings/policies', label: 'ABAC-Richtlinien', icon: '\ud83d\udee1\ufe0f' },
     { to: '/settings/guests', label: 'Gäste', icon: '\ud83d\udc64' },
+    { to: '/settings/ownership', label: 'Besitzübertragung', icon: '\ud83d\udce4' },
   ];
 
   const existingPaths = new Set(hardcodedNavItems.map(item => item.to));

frontend/src/pages/SettingsExternalAgents.tsx

@@ -0,0 +1,150 @@
+/**
+ * External Agents API settings page — integration guide for external
+ * systems (UI-Backlog module 15/16).
+ *
+ * Backend: /api/v1/external/agent (ai_assistant plugin, external_api.py).
+ * - POST /{agent_id}/run    → run agent (Bearer auth, 10 req/min)
+ * - GET  /{agent_id}/status → agent status + run stats
+ * - POST /{agent_id}/stream → SSE stream
+ *
+ * These endpoints are Bearer-token-only (no session cookies) — meant for
+ * external systems (n8n, scripts, other apps). This page lists the
+ * tenant's AI agents and renders copy-paste curl snippets per agent.
+ */
+
+import React, { useState } from 'react';
+import { useTranslation } from 'react-i18next';
+import { Link } from 'react-router-dom';
+import { Bot, Copy, Check, Inbox } from 'lucide-react';
+import {
+  useAiAgents,
+  buildCurlSnippets,
+  curlCommand,
+  type AIAgent,
+} from '@/api/externalAgent';
+import { Card } from '@/components/ui/Card';
+import { Badge } from '@/components/ui/Badge';
+import { Button } from '@/components/ui/Button';
+import { EmptyState } from '@/components/ui/EmptyState';
+import { Skeleton } from '@/components/ui/Skeleton';
+
+function CopyButton({ text, testId }: { text: string; testId: string }) {
+  const [copied, setCopied] = useState(false);
+  const copy = async () => {
+    try {
+      await navigator.clipboard.writeText(text);
+      setCopied(true);
+      setTimeout(() => setCopied(false), 2000);
+    } catch {
+      // clipboard API unavailable — user can select manually
+    }
+  };
+  return (
+    <Button
+      variant="ghost"
+      size="sm"
+      onClick={copy}
+      aria-label="copy"
+      data-testid={testId}
+    >
+      {copied ? (
+        <Check className="w-4 h-4 text-success-600" aria-hidden="true" />
+      ) : (
+        <Copy className="w-4 h-4" aria-hidden="true" />
+      )}
+    </Button>
+  );
+}
+
+function AgentCard({ agent }: { agent: AIAgent }) {
+  const { t } = useTranslation();
+  const snippets = buildCurlSnippets(agent.id);
+
+  return (
+    <Card className="p-4" data-testid={`external-agent-card-${agent.id}`}>
+      <div className="flex items-center gap-2 mb-3">
+        <Bot className="w-4 h-4 text-primary-600 flex-shrink-0" aria-hidden="true" />
+        <span className="text-sm font-medium text-secondary-900 dark:text-secondary-100">
+          {agent.name}
+        </span>
+        <Badge variant={agent.is_active ? 'success' : 'secondary'} dot>
+          {agent.is_active ? t('common.active') : t('common.inactive')}
+        </Badge>
+      </div>
+      {agent.description && (
+        <p className="text-xs text-secondary-500 dark:text-secondary-400 mb-3">
+          {agent.description}
+        </p>
+      )}
+      <div className="space-y-2">
+        {snippets.map((snippet) => (
+          <div
+            key={snippet.description}
+            className="bg-secondary-50 dark:bg-secondary-900/50 rounded-lg p-3"
+            data-testid={`curl-snippet-${agent.id}-${snippet.description}`}
+          >
+            <div className="flex items-center justify-between gap-2 mb-1">
+              <span className="text-xs font-medium text-secondary-600 dark:text-secondary-300">
+                {snippet.description}
+              </span>
+              <CopyButton
+                text={curlCommand(snippet)}
+                testId={`curl-copy-${agent.id}-${snippet.description}`}
+              />
+            </div>
+            <pre className="text-xs text-secondary-700 dark:text-secondary-200 overflow-x-auto whitespace-pre-wrap break-all">
+              {curlCommand(snippet)}
+            </pre>
+          </div>
+        ))}
+      </div>
+    </Card>
+  );
+}
+
+export function SettingsExternalAgentsPage() {
+  const { t } = useTranslation();
+  const { data: agents, isLoading } = useAiAgents();
+
+  const items = agents ?? [];
+
+  return (
+    <div className="p-6 max-w-4xl mx-auto" data-testid="settings-external-agents-page">
+      <div className="flex items-center justify-between mb-2">
+        <h1 className="text-2xl font-bold text-secondary-900">
+          {t('settings.externalAgents')}
+        </h1>
+      </div>
+      <p className="text-sm text-secondary-500 mb-4">{t('settings.externalAgentsHint')}</p>
+      <div className="mb-6 rounded-lg bg-primary-50 dark:bg-primary-900/20 border border-primary-200 dark:border-primary-800 p-4">
+        <p className="text-xs text-primary-800 dark:text-primary-200">
+          {t('settings.externalAgentsAuthHint')}{' '}
+          <Link
+            to="/settings/api-tokens"
+            className="font-medium underline underline-offset-2"
+          >
+            {t('settings.externalAgentsTokenLink')}
+          </Link>
+        </p>
+      </div>
+
+      {isLoading ? (
+        <div data-testid="external-agents-skeleton" className="space-y-3">
+          <Skeleton className="h-28" />
+          <Skeleton className="h-28" />
+        </div>
+      ) : items.length === 0 ? (
+        <EmptyState
+          icon={<Inbox className="w-8 h-8 text-secondary-400" aria-hidden="true" />}
+          title={t('settings.noExternalAgents')}
+        />
+      ) : (
+        <div className="space-y-4">
+          {items.map((agent) => (
+            <AgentCard key={agent.id} agent={agent} />
+          ))}
+        </div>
+      )}
+    </div>
+  );
+}

frontend/src/pages/SettingsOwnership.tsx

@@ -0,0 +1,208 @@
+/**
+ * Ownership transfer settings page — admin bulk ownership transfer
+ * (UI-Backlog module 16/16).
+ *
+ * Backend: POST /api/v1/ownership/transfer (require_admin).
+ * Transfers all records (owner_id) from one user to another, optionally
+ * scoped to selected entity types (10 known types). Use case: employee
+ * leaves the company — their records move to the successor.
+ */
+
+import React, { useMemo, useState } from 'react';
+import { useTranslation } from 'react-i18next';
+import { Lock } from 'lucide-react';
+import { asError } from '@/utils/errorTypes';
+import {
+  useTransferOwnership,
+  OWNERSHIP_ENTITY_TYPES,
+  type OwnershipTransferResult,
+} from '@/api/ownership';
+import { useUsers, type UserResponse } from '@/api/users';
+import { useAuthStore } from '@/store/authStore';
+import { useToast } from '@/components/ui/Toast';
+import { Card } from '@/components/ui/Card';
+import { Button } from '@/components/ui/Button';
+import { Badge } from '@/components/ui/Badge';
+import { Select } from '@/components/ui/Select';
+import { ConfirmDialog } from '@/components/ui/ConfirmDialog';
+import { Skeleton } from '@/components/ui/Skeleton';
+
+export function SettingsOwnershipPage() {
+  const { t } = useTranslation();
+  const toast = useToast();
+  const user = useAuthStore((state) => state.user);
+  const isAdmin = user?.is_system_admin === true;
+
+  const { data: usersData, isLoading } = useUsers(1, 100);
+  const transferMutation = useTransferOwnership();
+
+  const [fromId, setFromId] = useState('');
+  const [toId, setToId] = useState('');
+  const [selectedTypes, setSelectedTypes] = useState<Set<string>>(new Set());
+  const [confirmOpen, setConfirmOpen] = useState(false);
+  const [result, setResult] = useState<OwnershipTransferResult | null>(null);
+
+  const users: UserResponse[] = usersData?.items ?? [];
+
+  const userOptions = useMemo(
+    () => users.map((u) => ({ value: u.id, label: `${u.name} (${u.email})` })),
+    [users],
+  );
+
+  const fromUser = users.find((u) => u.id === fromId);
+  const toUser = users.find((u) => u.id === toId);
+
+  if (!isAdmin) {
+    return (
+      <div className="flex items-center justify-center min-h-[50vh]" role="alert">
+        <div className="text-center">
+          <Lock className="w-10 h-10 mx-auto text-secondary-400" aria-hidden="true" />
+          <p className="mt-3 text-sm text-secondary-600" data-testid="ownership-admin-only">
+            {t('settings.ownershipAdminOnly')}
+          </p>
+        </div>
+      </div>
+    );
+  }
+
+  const toggleType = (entityType: string) => {
+    setSelectedTypes((prev) => {
+      const next = new Set(prev);
+      if (next.has(entityType)) {
+        next.delete(entityType);
+      } else {
+        next.add(entityType);
+      }
+      return next;
+    });
+  };
+
+  const handleTransfer = async () => {
+    try {
+      const payload = {
+        from_user_id: fromId,
+        to_user_id: toId,
+        entity_types: selectedTypes.size > 0 ? Array.from(selectedTypes) : null,
+      };
+      const res = await transferMutation.mutateAsync(payload);
+      setResult(res);
+      toast.success(t('settings.ownershipTransferred'));
+      setConfirmOpen(false);
+    } catch (err: unknown) {
+      const errObj = asError(err);
+      toast.error(errObj.message || t('common.error'));
+      setConfirmOpen(false);
+    }
+  };
+
+  const canSubmit = fromId && toId && fromId !== toId;
+
+  return (
+    <div className="p-6 max-w-4xl mx-auto" data-testid="settings-ownership-page">
+      <div className="flex items-center justify-between mb-2">
+        <h1 className="text-2xl font-bold text-secondary-900">{t('settings.ownership')}</h1>
+      </div>
+      <p className="text-sm text-secondary-500 mb-6">{t('settings.ownershipHint')}</p>
+
+      {isLoading ? (
+        <div data-testid="ownership-skeleton" className="space-y-3">
+          <Skeleton className="h-20" />
+          <Skeleton className="h-20" />
+        </div>
+      ) : (
+        <Card className="p-5">
+          <div className="space-y-5" data-testid="ownership-form">
+            <div className="grid gap-4 sm:grid-cols-2">
+              <Select
+                label={t('settings.ownershipFrom')}
+                options={[{ value: '', label: '—' }, ...userOptions]}
+                value={fromId}
+                onChange={(e) => setFromId(e.target.value)}
+                data-testid="ownership-from"
+              />
+              <Select
+                label={t('settings.ownershipTo')}
+                options={[{ value: '', label: '—' }, ...userOptions]}
+                value={toId}
+                onChange={(e) => setToId(e.target.value)}
+                data-testid="ownership-to"
+              />
+            </div>
+
+            <div>
+              <p className="text-sm font-medium text-secondary-900 mb-2">
+                {t('settings.ownershipEntityTypes')}{' '}
+                <span className="text-secondary-500 font-normal">
+                  ({t('settings.ownershipAllHint')})
+                </span>
+              </p>
+              <div className="flex flex-wrap gap-2">
+                {OWNERSHIP_ENTITY_TYPES.map((et) => (
+                  <button
+                    key={et}
+                    type="button"
+                    onClick={() => toggleType(et)}
+                    className={
+                      selectedTypes.has(et)
+                        ? 'px-3 py-1.5 rounded-full text-sm font-medium bg-primary-100 text-primary-700 border border-primary-300'
+                        : 'px-3 py-1.5 rounded-full text-sm font-medium bg-secondary-100 text-secondary-700 border border-secondary-200 hover:bg-secondary-200'
+                    }
+                    aria-pressed={selectedTypes.has(et)}
+                    data-testid={`ownership-type-${et}`}
+                  >
+                    {t(`settings.ownershipType_${et}`, et)}
+                  </button>
+                ))}
+              </div>
+            </div>
+
+            <div className="flex justify-end">
+              <Button
+                onClick={() => setConfirmOpen(true)}
+                disabled={!canSubmit || transferMutation.isPending}
+                data-testid="ownership-submit-btn"
+              >
+                {t('settings.ownershipTransfer')}
+              </Button>
+            </div>
+          </div>
+        </Card>
+      )}
+
+      {result && (
+        <Card className="p-5 mt-6" data-testid="ownership-result">
+          <h2 className="text-lg font-semibold text-secondary-900 mb-3">
+            {t('settings.ownershipResult')}
+          </h2>
+          <div className="space-y-2">
+            {Object.entries(result.results).map(([entityType, count]) => (
+              <div key={entityType} className="flex items-center justify-between text-sm">
+                <span className="text-secondary-700">
+                  {t(`settings.ownershipType_${entityType}`, entityType)}
+                </span>
+                <Badge variant={count > 0 ? 'success' : 'secondary'}>{count}</Badge>
+              </div>
+            ))}
+          </div>
+        </Card>
+      )}
+
+      <ConfirmDialog
+        open={confirmOpen}
+        title={t('settings.ownershipTransfer')}
+        message={
+          fromUser && toUser
+            ? `${t('settings.ownershipConfirm')}: ${fromUser.name} → ${toUser.name}? (${
+                selectedTypes.size > 0
+                  ? t('settings.ownershipSelectedTypes', { count: selectedTypes.size })
+                  : t('settings.ownershipAllTypes')
+              })`
+            : ''
+        }
+        variant="danger"
+        onConfirm={handleTransfer}
+        onCancel={() => setConfirmOpen(false)}
+      />
+    </div>
+  );
+}