Add entity CRUD events over WebSocket with auto-refresh

Broadcast entity_changed and device_health_changed events via the event
bus so the frontend can auto-refresh cards without polling. Adds
exponential backoff on WS reconnect.

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

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

@@ -12,6 +12,7 @@ from PIL import Image
 
 from wled_controller.api.auth import AuthRequired
 from wled_controller.api.dependencies import (
+    fire_entity_event,
     get_color_strip_store,
     get_device_store,
     get_pattern_template_store,
@@ -181,6 +182,7 @@ async def create_target(
         except ValueError as e:
             logger.warning(f"Could not register target {target.id} in processor manager: {e}")
 
+        fire_entity_event("output_target", "created", target.id)
         return _target_to_response(target)
 
     except HTTPException:
@@ -319,6 +321,7 @@ async def update_target(
         except ValueError:
             pass
 
+        fire_entity_event("output_target", "updated", target_id)
         return _target_to_response(target)
 
     except HTTPException:
@@ -354,6 +357,7 @@ async def delete_target(
         # Delete from store
         target_store.delete_target(target_id)
 
+        fire_entity_event("output_target", "deleted", target_id)
         logger.info(f"Deleted target {target_id}")
 
     except ValueError as e: