Phase 3.5: Automation & Agents Plugin

Neues automation Plugin (app/plugins/builtins/automation/):
- 7 DB-Modelle: AgentDefinition, AgentVersion, AutomationDefinition,
  AutomationVersion, AutomationCronJob, AgentRun, AutomationRun
- Migration 0001_initial.sql mit allen Tabellen + RLS
- PluginManifest erweitert: agent_definitions, automation_templates,
  cron_jobs, heartbeat_configs, miniapps Contribution-Felder
- 21 API-Endpoints: /api/v1/automation (CRUD, execute, dry-run,
  runs, versions, restore, settings, miniapps) + /api/v1/agents
  (CRUD, execute, test-run, runs, versions, restore, tools, send-message)

Backend Features:
- Cron-Scheduler (scheduler.py): ARQ-basiert, liest CronJob-Tabelle,
  enqueued run_agent/run_automation, croniter fuer next_run_at
- Workflow-Timeout-Worker (workflow_timeout.py): prueft abgelaufene
  WorkflowInstances, setzt cancelled, sendet Notification
- Agent Runner (agent_runner.py): LiteLLM + ToolRegistry, proactive/
  reactive mode, Rate-Limiting, Budget-Limit, Infinite-Loop-Detection
- Automation Execution Engine (execution_engine.py): Condition
  evaluation (eq/ne/gt/lt/contains/exists), Actions (api_call/
  notification/workflow_start), Dry-Run mode
- Agent-to-Agent Communication (agent_comm.py): send_agent_message
  tool, kommunikation plugin integration
- Plugin-Beitraege: register/unregister on activate/deactivate,
  Konfliktloesung mit Plugin-Name als Prefix
- Heartbeat-Migration: ai_proactive heartbeat als Cron-Job
- Versionshistorie: Auto-Versioning bei Updates, Restore-Endpoint
- Settings: GET/PATCH /api/v1/automation/settings
- ARQ Worker: 11 functions, 2 cron_jobs (scheduler_tick 30s,
  check_workflow_timeouts 5min)

Frontend:
- AutomationDashboard.tsx: Automation Builder UI mit Trigger,
  Conditions, Actions, Execute, Dry-Run, Run-History, Versions
- AgentDashboard.tsx: Agent Builder UI mit Model, Tools, Prompt,
  Heartbeat, Rate-Limits, Execute, Test-Run, Agent-Chat
- AutomationSettings.tsx: Settings + MiniApp-Builder
- automation.ts: 24 React Query Hooks
- automation.ts types: TypeScript Interfaces
- routes/index.tsx: /automation, /agents, /settings/automation

Tests:
- 22 Frontend-Tests (AutomationDashboard, AgentDashboard, API) — alle bestanden
- Backend-Tests: test_automation.py (CRUD, versions, conditions, dry-run, rate-limiting)
- TSC: keine neuen Errors (nur pre-existing Dms.tsx)
- croniter dependency installiert

frontend/src/routes/index.tsx

@@ -35,6 +35,9 @@ const AIAssistantPage = React.lazy(() => import('@/pages/AIAssistant').then(m =>
 const AISettingsPage = React.lazy(() => import('@/pages/AISettings').then(m => ({ default: m.AISettingsPage })));
 const ProactiveAISettings = React.lazy(() => import('@/pages/ProactiveAISettings').then(m => ({ default: m.ProactiveAISettings })));
 const SettingsThemePage = React.lazy(() => import('@/pages/SettingsTheme').then(m => ({ default: m.SettingsThemePage })));
+const AutomationDashboardPage = React.lazy(() => import('@/pages/AutomationDashboard').then(m => ({ default: m.AutomationDashboardPage })));
+const AgentDashboardPage = React.lazy(() => import('@/pages/AgentDashboard').then(m => ({ default: m.AgentDashboardPage })));
+const AutomationSettingsPage = React.lazy(() => import('@/pages/AutomationSettings').then(m => ({ default: m.AutomationSettingsPage })));
 
 /** Centered spinner fallback for lazy-loaded routes */
 function PageLoader() {
@@ -83,6 +86,8 @@ const router = createBrowserRouter([
       { path: '/mail', element: withSuspense(<MailPage />) },
       { path: '/mail/settings', element: withSuspense(<MailSettingsPage />) },
       { path: '/ai-assistant', element: withSuspense(<AIAssistantPage />) },
+      { path: '/automation', element: withSuspense(<AutomationDashboardPage />) },
+      { path: '/agents', element: withSuspense(<AgentDashboardPage />) },
       { path: '/profile', element: withSuspense(<SettingsProfilePage />) },
       {
         path: '/settings',
@@ -101,6 +106,7 @@ const router = createBrowserRouter([
           { path: 'ai', element: withSuspense(<AISettingsPage />) },
           { path: 'ai-proactive', element: withSuspense(<ProactiveAISettings />) },
           { path: 'theme', element: withSuspense(<SettingsThemePage />) },
+          { path: 'automation', element: withSuspense(<AutomationSettingsPage />) },
           { path: '*', element: <PluginRouteRenderer /> },
         ],
       },