best thumbnail endpoint should pass correct extension param (#19930)

docs/docs/configuration/camera_specific.md

@@ -147,6 +147,7 @@ WEB Digest Algorithm  - MD5
 Reolink has many different camera models with inconsistently supported features and behavior. The below table shows a summary of various features and recommendations.
 
 | Camera Resolution | Camera Generation         | Recommended Stream Type           | Additional Notes                                                        |
+| ----------------  | ------------------------- | --------------------------------  | ----------------------------------------------------------------------- |
 | 5MP or lower      | All                       | http-flv                          | Stream is h264                                                          |
 | 6MP or higher     | Latest (ex: Duo3, CX-8##) | http-flv with ffmpeg 8.0, or rtsp | This uses the new http-flv-enhanced over H265 which requires ffmpeg 8.0 |
 | 6MP or higher     | Older (ex: RLC-8##)       | rtsp                              |                                                                         |

frigate/api/media.py

@@ -1598,7 +1598,7 @@ def label_thumbnail(request: Request, camera_name: str, label: str):
     try:
         event_id = event_query.scalar()
 
-        return event_thumbnail(request, event_id, 60)
+        return event_thumbnail(request, event_id, Extension.jpg, 60)
     except DoesNotExist:
         frame = np.zeros((175, 175, 3), np.uint8)
         ret, jpg = cv2.imencode(".jpg", frame, [int(cv2.IMWRITE_JPEG_QUALITY), 70])