Handle OSError in get_latest_mtime during directory walk

Catch OSError when statting files during the recursive directory
walk. This handles cases like symbolic link loops or other filesystem
issues in local add-on directories without crashing the store load.

Fixes SUPERVISOR-1FJ0

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

supervisor/utils/__init__.py

@@ -146,9 +146,8 @@ def get_latest_mtime(directory: Path) -> tuple[float, Path]:
             if mtime > latest_mtime:
                 latest_mtime = mtime
                 latest_path = path
-        except FileNotFoundError:
-            # File might disappear between listing and stat. Parent
-            # directory modification date will flag such a change.
+        except OSError:
+            _LOGGER.debug("Could not stat %s, skipping", path)
             continue
     return latest_mtime, latest_path