Phase 5.1-5.4: PWA, Public Plugin Endpoints, Contacts Embedding, Search Coverage

5.1 Public Plugin Endpoints:
- PluginRouteDef.is_public field in manifest.py
- main.py: public routes mounted without auth dependency
- permissions/public_routes.py: token-based share link access (info, verify, download)
- permissions/plugin.py: public share route registered with is_public=True

5.2 PWA:
- vite.config.ts: VitePWA plugin configured (autoUpdate, workbox, runtime caching)
- frontend/public/manifest.json: PWA manifest with icons
- index.html: theme-color, manifest link, apple-touch-icon, apple-mobile-web-app meta
- Build generates sw.js + workbox (90 precache entries)

5.3 Contacts Embedding:
- contact.py: embedding column (Vector(768)) added to Contact model
- Migration 0002_embeddings.sql already exists (adds embedding + HNSW index)
- ContactSearchProvider already queries embedding column

5.4 Search Coverage:
- 5 new search providers: task, contactperson, tag, conversation, user
- All providers implement FTS search with tenant_id + deleted_at filters
- TagSearchProvider also supports vector search (384-dim embedding)
- provider_registry.py: all 5 new providers auto-registered
- Total: 10 search providers (was 5)

app/plugins/builtins/unified_search/provider_registry.py

@@ -115,6 +115,21 @@ async def auto_register_providers(db: AsyncSession) -> None:
     from app.plugins.builtins.unified_search.providers.company_provider import (
         CompanySearchProvider,
     )
+    from app.plugins.builtins.unified_search.providers.task_provider import (
+        TaskSearchProvider,
+    )
+    from app.plugins.builtins.unified_search.providers.contactperson_provider import (
+        ContactPersonSearchProvider,
+    )
+    from app.plugins.builtins.unified_search.providers.tag_provider import (
+        TagSearchProvider,
+    )
+    from app.plugins.builtins.unified_search.providers.conversation_provider import (
+        ConversationSearchProvider,
+    )
+    from app.plugins.builtins.unified_search.providers.user_provider import (
+        UserSearchProvider,
+    )
 
     registry = get_search_registry()
     registry.clear()
@@ -126,6 +141,11 @@ async def auto_register_providers(db: AsyncSession) -> None:
         FileSearchProvider,
         EventSearchProvider,
         CompanySearchProvider,
+        TaskSearchProvider,
+        ContactPersonSearchProvider,
+        TagSearchProvider,
+        ConversationSearchProvider,
+        UserSearchProvider,
     ]:
         try:
             registry.register(provider_cls())