Fix FAT dashcam file deletion

Co-authored-by: Copilot <[email protected]>

modules/app_dash.py

@@ -292,6 +292,24 @@ def _safe_video_path(source_folder, relative_path):
     return target_real
 
 
+def _remove_video_file(path):
+    try:
+        os.remove(path)
+        return
+    except PermissionError:
+        pass
+
+    try:
+        subprocess.run(
+            ["sudo", "rm", "--", path],
+            capture_output=True,
+            text=True,
+            check=True,
+        )
+    except subprocess.CalledProcessError as e:
+        raise OSError(e.stderr.strip() or f"Failed to delete {path}") from e
+
+
 def delete_dashcam_files(relative_path=None, delete_all=False, mount_point=DEFAULT_MOUNT_POINT):
     """Delete one or all dashcam videos, restoring read-only state afterward."""
     if not delete_all and relative_path is None:
@@ -336,7 +354,7 @@ def delete_dashcam_files(relative_path=None, delete_all=False, mount_point=DEFAU
                 for _abs_path, rel_path in targets:
                     try:
                         safe_path = _safe_video_path(source, rel_path)
-                        os.remove(safe_path)
+                        _remove_video_file(safe_path)
                         deleted.append(rel_path)
                     except (OSError, ValueError) as e:
                         errors.append(f"{rel_path}: {e}")