Refactor app helpers and use AppStateDep in config router

Move service-dependent helper wrappers from app.utils to app.helpers and update config router activation/rollback to use explicit AppState dependency.

backend/app/helpers/config_file_helpers.py

@@ -0,0 +1,19 @@
+"""Shared config-file helpers reused across service modules."""
+
+from __future__ import annotations
+
+from app.services.config_file_service import (
+    _build_inactive_jail,
+    _get_active_jail_names,
+    _ordered_config_files,
+    _parse_jails_sync,
+    _validate_jail_config_sync,
+)
+
+__all__ = [
+    "_ordered_config_files",
+    "_parse_jails_sync",
+    "_build_inactive_jail",
+    "_get_active_jail_names",
+    "_validate_jail_config_sync",
+]