Set writable YOLO config directory

backend/README.md

@@ -231,6 +231,9 @@ AI-enabled Docker images include the native OpenCV runtime libraries required by
 Ultralytics. Dependency availability is checked with real `torch` and
 `ultralytics` imports, so missing shared libraries are reported as
 `dependency_unavailable` instead of being treated as configured.
+Docker/Unraid runtimes set `YOLO_CONFIG_DIR` to a writable storage path so
+Ultralytics does not attempt to write settings under the root user config
+directory.
 
 Configured YOLO requires:
 
@@ -269,6 +272,7 @@ Optional tuning:
 YOLO_MODEL_ID=yolo-configured
 YOLO_MODEL_DISPLAY_NAME="Configured YOLO detector"
 YOLO_MODEL_VERSION=local-v1
+YOLO_CONFIG_DIR=/app/storage/ultralytics
 YOLO_DEVICE=cpu
 YOLO_IMAGE_SIZE=640
 YOLO_MAX_TILES=100