Add tags to all entity types with chip-based input and autocomplete

- Add `tags: List[str]` field to all 13 entity types (devices, output targets,
  CSS sources, picture sources, audio sources, value sources, sync clocks,
  automations, scene presets, capture/audio/PP/pattern templates)
- Update all stores, schemas, and route handlers for tag CRUD
- Add GET /api/v1/tags endpoint aggregating unique tags across all stores
- Create TagInput component with chip display, autocomplete dropdown,
  keyboard navigation, and API-backed suggestions
- Display tag chips on all entity cards (searchable via existing text filter)
- Add tag input to all 14 editor modals with dirty check support
- Add CSS styles and i18n keys (en/ru/zh) for tag UI
- Also includes code review fixes: thread safety, perf, store dedup

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

server/src/wled_controller/api/routes/output_targets.py

@@ -105,6 +105,7 @@ def _target_to_response(target) -> OutputTargetResponse:
             adaptive_fps=target.adaptive_fps,
             protocol=target.protocol,
             description=target.description,
+            tags=getattr(target, 'tags', []),
 
             created_at=target.created_at,
             updated_at=target.updated_at,
@@ -117,6 +118,7 @@ def _target_to_response(target) -> OutputTargetResponse:
             picture_source_id=target.picture_source_id,
             key_colors_settings=_kc_settings_to_schema(target.settings),
             description=target.description,
+            tags=getattr(target, 'tags', []),
 
             created_at=target.created_at,
             updated_at=target.updated_at,
@@ -127,6 +129,7 @@ def _target_to_response(target) -> OutputTargetResponse:
             name=target.name,
             target_type=target.target_type,
             description=target.description,
+            tags=getattr(target, 'tags', []),
 
             created_at=target.created_at,
             updated_at=target.updated_at,
@@ -169,6 +172,7 @@ async def create_target(
             picture_source_id=data.picture_source_id,
             key_colors_settings=kc_settings,
             description=data.description,
+            tags=data.tags,
         )
 
         # Register in processor manager
@@ -287,6 +291,7 @@ async def update_target(
             protocol=data.protocol,
             key_colors_settings=kc_settings,
             description=data.description,
+            tags=data.tags,
         )
 
         # Detect KC brightness VS change (inside key_colors_settings)
@@ -461,11 +466,11 @@ async def get_target_colors(
                 r=r, g=g, b=b,
                 hex=f"#{r:02x}{g:02x}{b:02x}",
             )
-        from datetime import datetime
+        from datetime import datetime, timezone
         return KeyColorsResponse(
             target_id=target_id,
             colors=colors,
-            timestamp=datetime.utcnow(),
+            timestamp=datetime.now(timezone.utc),
         )
     except ValueError as e:
         raise HTTPException(status_code=404, detail=str(e))