feat: unified_search + ai_proactive plugins with Ollama Cloud DeepSeek V4

- unified_search: Hybride Suche (PostgreSQL FTS + pgvector + RRF Fusion)
  - 5 Search Providers (Contact, Company, Mail, File, Event)
  - KI Query Understanding (Fuzzy, Facetten via LiteLLM)
  - DMS Text-Extraction (PDF, DOCX, XLSX, PPTX)
  - Embedding Pipeline (ollama/nomic-embed-text, 768 Dim)
  - Background Jobs für Indexierung
  - Plugin-basierte Provider Registry

- ai_proactive: Proaktiver KI-Agent
  - Context-Tracking (Frontend → Backend → Event Bus)
  - Proactive Engine mit LLM Suggestion-Generierung
  - SSE Real-time Push an Frontend
  - 6 AI Tools für Tool Registry
  - Rate-Limiting + User Settings
  - Deep Analysis Background Jobs

- Frontend Integration:
  - useAIContext Hook, SuggestionSidebar, SuggestionBadge
  - ProactiveAISettings Page, Search API Client
  - Globale Suche auf neue API umgestellt

- Tests: test_unified_search.py + test_ai_proactive.py (alle bestanden)
- Config: Ollama Cloud DeepSeek V4 als Default, konfigurierbar
- Dependencies: PyMuPDF, python-docx, python-pptx, pgvector
- Bugfixes: notification type_key length, migration IF NOT EXISTS

frontend/src/routes/index.tsx

@@ -33,6 +33,7 @@ import { MailSettingsPage } from '@/pages/MailSettings';
 import { SettingsNotificationsPage } from '@/pages/SettingsNotifications';
 import { AIAssistantPage } from '@/pages/AIAssistant';
 import { AISettingsPage } from '@/pages/AISettings';
+import { ProactiveAISettings } from '@/pages/ProactiveAISettings';
 
 const router = createBrowserRouter([
   {
@@ -89,6 +90,7 @@ const router = createBrowserRouter([
           { path: 'mail', element: <MailSettingsPage /> },
           { path: 'notifications', element: <SettingsNotificationsPage /> },
           { path: 'ai', element: <AISettingsPage /> },
+          { path: 'ai-proactive', element: <ProactiveAISettings /> },
         ],
       },
     ],