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/templates.py

@@ -10,6 +10,7 @@ from fastapi import APIRouter, HTTPException, Depends, Query, WebSocket, WebSock
 
 from wled_controller.api.auth import AuthRequired
 from wled_controller.api.dependencies import (
+    fire_entity_event,
     get_picture_source_store,
     get_pp_template_store,
     get_template_store,
@@ -96,6 +97,7 @@ async def create_template(
             tags=template_data.tags,
         )
 
+        fire_entity_event("capture_template", "created", template.id)
         return TemplateResponse(
             id=template.id,
             name=template.name,
@@ -156,6 +158,7 @@ async def update_template(
             tags=update_data.tags,
         )
 
+        fire_entity_event("capture_template", "updated", template_id)
         return TemplateResponse(
             id=template.id,
             name=template.name,
@@ -202,6 +205,7 @@ async def delete_template(
 
         # Proceed with deletion
         template_store.delete_template(template_id)
+        fire_entity_event("capture_template", "deleted", template_id)
 
     except HTTPException:
         raise  # Re-raise HTTP exceptions as-is