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/audio_templates.py

@@ -8,7 +8,7 @@ from fastapi import APIRouter, HTTPException, Depends, Query
 from starlette.websockets import WebSocket, WebSocketDisconnect
 
 from wled_controller.api.auth import AuthRequired
-from wled_controller.api.dependencies import get_audio_template_store, get_audio_source_store, get_processor_manager
+from wled_controller.api.dependencies import fire_entity_event, get_audio_template_store, get_audio_source_store, get_processor_manager
 from wled_controller.api.schemas.audio_templates import (
     AudioEngineInfo,
     AudioEngineListResponse,
@@ -66,6 +66,7 @@ async def create_audio_template(
             engine_config=data.engine_config, description=data.description,
             tags=data.tags,
         )
+        fire_entity_event("audio_template", "created", template.id)
         return AudioTemplateResponse(
             id=template.id, name=template.name, engine_type=template.engine_type,
             engine_config=template.engine_config, tags=getattr(template, 'tags', []),
@@ -112,6 +113,7 @@ async def update_audio_template(
             engine_type=data.engine_type, engine_config=data.engine_config,
             description=data.description, tags=data.tags,
         )
+        fire_entity_event("audio_template", "updated", template_id)
         return AudioTemplateResponse(
             id=t.id, name=t.name, engine_type=t.engine_type,
             engine_config=t.engine_config, tags=getattr(t, 'tags', []),
@@ -135,6 +137,7 @@ async def delete_audio_template(
     """Delete an audio template."""
     try:
         store.delete_template(template_id, audio_source_store=audio_source_store)
+        fire_entity_event("audio_template", "deleted", template_id)
     except HTTPException:
         raise
     except ValueError as e: