Add manual ping/health check button to device cards

Adds a refresh icon button on each device card that triggers an immediate
health check via POST /devices/{id}/ping, showing online status with
latency or offline result as a toast notification.

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

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

@@ -406,6 +406,26 @@ async def get_device_state(
         raise HTTPException(status_code=404, detail=str(e))
 
 
+@router.post("/api/v1/devices/{device_id}/ping", response_model=DeviceStateResponse, tags=["Devices"])
+async def ping_device(
+    device_id: str,
+    _auth: AuthRequired,
+    store: DeviceStore = Depends(get_device_store),
+    manager: ProcessorManager = Depends(get_processor_manager),
+):
+    """Force an immediate health check on a device."""
+    device = store.get_device(device_id)
+    if not device:
+        raise HTTPException(status_code=404, detail=f"Device {device_id} not found")
+
+    try:
+        state = await manager.force_device_health_check(device_id)
+        state["device_type"] = device.device_type
+        return DeviceStateResponse(**state)
+    except ValueError as e:
+        raise HTTPException(status_code=404, detail=str(e))
+
+
 # ===== WLED BRIGHTNESS ENDPOINTS =====
 
 @router.get("/api/v1/devices/{device_id}/brightness", tags=["Settings"])