feat(M5): Plugin-MiniApps — dms, mail, wiki, graph_rag, automation (#363)

- 5 Manifest-Beiträge (MiniAppContribution): dms_folders (dms:read), mail_unread (mail:read), wiki_recent (wiki:read), graph_overview (graph:read), automation_status (automation:read) — je settings_schema max_items, order 60-100
- 5 Frontend-Widgets auf bestehenden API-Clients (keine neuen Backend-Endpoints): DmsFoldersWidget, MailUnreadWidget, WikiRecentWidget, GraphOverviewWidget, AutomationStatusWidget
- MiniAppHost-Registry +5; tsc clean, build OK
- Tests: M5 7/7 (TDD rot->gruen), Backend-Regression 53/53, Vitest 22/22

app/plugins/builtins/graph_rag/plugin.py

@@ -3,7 +3,7 @@
 from __future__ import annotations
 
 from app.plugins.base import BasePlugin
-from app.plugins.manifest import PluginManifest, PluginRouteDef
+from app.plugins.manifest import MiniAppContribution, PluginManifest, PluginRouteDef
 
 
 class GraphRAGPlugin(BasePlugin):
@@ -24,6 +24,25 @@ class GraphRAGPlugin(BasePlugin):
         ],
         events=[],
         migrations=["0001_initial.sql"],
+        miniapps=[
+            MiniAppContribution(
+                app_id="graph_overview",
+                name="Wissens-Graph",
+                icon="Share2",
+                description="Beziehungsübersicht des Knowledge-Graphs.",
+                permission="graph:read",
+                settings_schema={
+                    "fields": [
+                        {"name": "max_items", "label": "Max. Beziehungen", "type": "number", "default": 6},
+                    ]
+                },
+                col_span=2,
+                row_span=1,
+                hosts=["chat", "dashboard", "window"],
+                component="@/components/dashboard/GraphOverviewWidget",
+                order=90,
+            ),
+        ],
         permissions=[
             "graph:read",
             "graph:write",