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/dependencies.py

@@ -157,6 +157,23 @@ def get_sync_clock_manager() -> SyncClockManager:
     return _sync_clock_manager
 
 
+def fire_entity_event(entity_type: str, action: str, entity_id: str) -> None:
+    """Fire an entity_changed event via the ProcessorManager event bus.
+
+    Args:
+        entity_type: e.g. "device", "output_target", "color_strip_source"
+        action: "created", "updated", or "deleted"
+        entity_id: The entity's unique ID
+    """
+    if _processor_manager is not None:
+        _processor_manager.fire_event({
+            "type": "entity_changed",
+            "entity_type": entity_type,
+            "action": action,
+            "id": entity_id,
+        })
+
+
 def init_dependencies(
     device_store: DeviceStore,
     template_store: TemplateStore,