Add power toggle button to LED device cards

WLED: native on/off via JSON API. Adalight: sends all-black frame
to blank LEDs (uses existing client if target is running, otherwise
opens temporary serial connection). Toggle button placed next to
delete button in card top-right corner.

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

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

@@ -1,4 +1,4 @@
-"""Device routes: CRUD, health state, brightness, calibration."""
+"""Device routes: CRUD, health state, brightness, power, calibration."""
 
 import httpx
 from fastapi import APIRouter, HTTPException, Depends
@@ -367,6 +367,63 @@ async def set_device_brightness(
         raise HTTPException(status_code=502, detail=f"Failed to reach device: {e}")
 
 
+# ===== POWER ENDPOINTS =====
+
+@router.get("/api/v1/devices/{device_id}/power", tags=["Settings"])
+async def get_device_power(
+    device_id: str,
+    _auth: AuthRequired,
+    store: DeviceStore = Depends(get_device_store),
+):
+    """Get current power state from the device."""
+    device = store.get_device(device_id)
+    if not device:
+        raise HTTPException(status_code=404, detail=f"Device {device_id} not found")
+    if "power_control" not in get_device_capabilities(device.device_type):
+        raise HTTPException(status_code=400, detail=f"Power control is not supported for {device.device_type} devices")
+
+    try:
+        provider = get_provider(device.device_type)
+        on = await provider.get_power(device.url)
+        return {"on": on}
+    except Exception as e:
+        logger.error(f"Failed to get power for {device_id}: {e}")
+        raise HTTPException(status_code=502, detail=f"Failed to reach device: {e}")
+
+
+@router.put("/api/v1/devices/{device_id}/power", tags=["Settings"])
+async def set_device_power(
+    device_id: str,
+    body: dict,
+    _auth: AuthRequired,
+    store: DeviceStore = Depends(get_device_store),
+    manager = Depends(get_processor_manager),
+):
+    """Turn device on or off."""
+    device = store.get_device(device_id)
+    if not device:
+        raise HTTPException(status_code=404, detail=f"Device {device_id} not found")
+    if "power_control" not in get_device_capabilities(device.device_type):
+        raise HTTPException(status_code=400, detail=f"Power control is not supported for {device.device_type} devices")
+
+    on = body.get("on")
+    if on is None or not isinstance(on, bool):
+        raise HTTPException(status_code=400, detail="'on' must be a boolean")
+
+    try:
+        if device.device_type == "adalight":
+            if not on:
+                await manager.send_black_frame(device_id)
+            # "on" is a no-op for Adalight — next processing frame lights them up
+        else:
+            provider = get_provider(device.device_type)
+            await provider.set_power(device.url, on)
+        return {"on": on}
+    except Exception as e:
+        logger.error(f"Failed to set power for {device_id}: {e}")
+        raise HTTPException(status_code=502, detail=f"Failed to reach device: {e}")
+
+
 # ===== CALIBRATION ENDPOINTS =====
 
 @router.get("/api/v1/devices/{device_id}/calibration", response_model=CalibrationSchema, tags=["Calibration"])