Add graph filter by entity type/running state and fix duplicate API calls

- Add entity type toggle pills and running/stopped filter to graph filter bar
- DataCache: return cached data if fresh, skip redundant fetches on page load
- Entity events: use force-fetch instead of invalidate+fetch to avoid stale gap
- Add no-cache middleware for static JS/CSS/JSON to prevent stale browser cache
- Reduces API calls on page load from ~70 to ~30

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

server/src/wled_controller/main.py

@@ -276,6 +276,14 @@ async def pwa_service_worker():
     )
 
 
+# Middleware: no-cache for static JS/CSS (development convenience)
+@app.middleware("http")
+async def _no_cache_static(request: Request, call_next):
+    response = await call_next(request)
+    if request.url.path.startswith("/static/") and request.url.path.endswith((".js", ".css", ".json")):
+        response.headers["Cache-Control"] = "no-cache, must-revalidate"
+    return response
+
 # Mount static files
 static_path = Path(__file__).parent / "static"
 if static_path.exists():