Remove PostgreSQL support and standardize on SQLite only.

Co-authored-by: Cursor <cursoragent@cursor.com>

modules/backup/routes.py

@@ -77,7 +77,7 @@ def register(deps) -> None:
     def api_backup_info(filename):
         try:
             path = resolve_backup_file(filename)
-            return jsonify(inspect_backup_archive(path, check_backend=True))
+            return jsonify(inspect_backup_archive(path))
         except (ValueError, FileNotFoundError) as exc:
             return jsonify({"error": str(exc)}), 404