feat: make manual-images list dynamic and resolve checkmark encoding issues

backend/fix_store_labels.py

@@ -17,7 +17,7 @@ def main():
 
     for mf in manual_files:
         try:
-            with open(mf, "r") as f:
+            with open(mf, "r", encoding="utf-8") as f:
                 data = json.load(f)
             
             is_modified = False