Add WLED brightness control, auto-name dialogs, and UI fixes

- Brightness slider now reads/writes actual WLED device brightness via
  new GET/PUT /devices/{id}/brightness endpoints (0-255 range)
- Cache last-known brightness to prevent slider jumping on card refresh
- Auto-generate names for stream, engine template, and PP template dialogs
- Fix sub-tabs not re-rendering on language change
- Add capture template icon (camera) to stream card pills
- Fix last calibration tutorial popup position

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

server/src/wled_controller/api/routes.py

@@ -667,6 +667,60 @@ async def update_settings(
         raise HTTPException(status_code=500, detail=str(e))
 
 
+# ===== WLED BRIGHTNESS ENDPOINT =====
+
+@router.get("/api/v1/devices/{device_id}/brightness", tags=["Settings"])
+async def get_device_brightness(
+    device_id: str,
+    _auth: AuthRequired,
+    store: DeviceStore = Depends(get_device_store),
+):
+    """Get current brightness from the WLED device."""
+    device = store.get_device(device_id)
+    if not device:
+        raise HTTPException(status_code=404, detail=f"Device {device_id} not found")
+
+    try:
+        async with httpx.AsyncClient(timeout=5.0) as http_client:
+            resp = await http_client.get(f"{device.url}/json/state")
+            resp.raise_for_status()
+            state = resp.json()
+            bri = state.get("bri", 255)
+            return {"brightness": bri}
+    except Exception as e:
+        logger.error(f"Failed to get WLED brightness for {device_id}: {e}")
+        raise HTTPException(status_code=502, detail=f"Failed to reach WLED device: {e}")
+
+
+@router.put("/api/v1/devices/{device_id}/brightness", tags=["Settings"])
+async def set_device_brightness(
+    device_id: str,
+    body: dict,
+    _auth: AuthRequired,
+    store: DeviceStore = Depends(get_device_store),
+):
+    """Set brightness on the WLED device directly."""
+    device = store.get_device(device_id)
+    if not device:
+        raise HTTPException(status_code=404, detail=f"Device {device_id} not found")
+
+    bri = body.get("brightness")
+    if bri is None or not isinstance(bri, int) or not 0 <= bri <= 255:
+        raise HTTPException(status_code=400, detail="brightness must be an integer 0-255")
+
+    try:
+        async with httpx.AsyncClient(timeout=5.0) as http_client:
+            resp = await http_client.post(
+                f"{device.url}/json/state",
+                json={"bri": bri},
+            )
+            resp.raise_for_status()
+            return {"brightness": bri}
+    except Exception as e:
+        logger.error(f"Failed to set WLED brightness for {device_id}: {e}")
+        raise HTTPException(status_code=502, detail=f"Failed to reach WLED device: {e}")
+
+
 # ===== CALIBRATION ENDPOINTS =====
 
 @router.get("/api/v1/devices/{device_id}/calibration", response_model=CalibrationSchema, tags=["Calibration"])