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/components/layout/AppShell.tsx

@@ -4,11 +4,17 @@ import { Sidebar } from './Sidebar';
 import { TopBar } from './TopBar';
 import { PluginToolbar } from './PluginToolbar';
 import { AISidebar } from './AISidebar';
+import { SuggestionSidebar } from '@/components/ai/SuggestionSidebar';
 import { ToastContainer } from '@/components/ui/Toast';
 import { useUIStore } from '@/store/uiStore';
+import { useAIContext } from '@/hooks/useAIContext';
 
 export function AppShell() {
   const location = useLocation();
+  const { suggestionSidebarOpen, toggleSuggestionSidebar } = useUIStore();
+
+  // Track context for AI Proactive suggestions
+  useAIContext();
 
   // Hide AI sidebar on the AI Assistant page itself
   const showAISidebar = !location.pathname.startsWith('/ai-assistant');
@@ -33,6 +39,11 @@ export function AppShell() {
       </div>
       {/* AI Sidebar — full height, right of TopBar and Toolbar */}
       {showAISidebar && <AISidebar />}
+      {/* Suggestion Sidebar — overlays from right */}
+      <SuggestionSidebar
+        isOpen={suggestionSidebarOpen}
+        onClose={() => toggleSuggestionSidebar()}
+      />
       <ToastContainer />
     </div>
   );