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/api/search.ts

@@ -0,0 +1,38 @@
+import { apiClient } from './client';
+
+export interface SearchResult {
+  type: 'company' | 'contact' | 'mail' | 'file' | 'event';
+  id: string;
+  name: string;
+  description?: string;
+  url: string;
+}
+
+export interface SearchResponse {
+  results: SearchResult[];
+  facets?: Record<string, Array<{ value: string; count: number }>>;
+  summary?: string;
+  suggestions?: string[];
+}
+
+export async function search(query: string, entityTypes?: string[], limit = 20): Promise<SearchResponse> {
+  const r = await apiClient.post('/api/v1/search', {
+    query,
+    entity_types: entityTypes,
+    limit,
+  });
+  return r.data;
+}
+
+export async function searchSuggest(q: string): Promise<string[]> {
+  const r = await apiClient.get('/api/v1/search/suggest', { params: { q } });
+  return r.data.suggestions;
+}
+
+export async function searchSimilar(entityType: string, entityId: string): Promise<SearchResult[]> {
+  const r = await apiClient.post('/api/v1/search/similar', {
+    entity_type: entityType,
+    entity_id: entityId,
+  });
+  return r.data.similar;
+}