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/__init__.py

@@ -0,0 +1,6 @@
+"""Cross-service helpers and shared abstractions.
+
+Modules in ``app.helpers`` are allowed to depend on the service layer when they
+implement shared business logic used by multiple service modules. This keeps
+``app.utils`` independent and low-level.
+"""

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",
+]

backend/app/helpers/jail_helpers.py

@@ -0,0 +1,23 @@
+"""Shared jail management helpers for service-layer code."""
+
+from __future__ import annotations
+
+from typing import TYPE_CHECKING
+
+from app.services.jail_service import reload_all
+
+if TYPE_CHECKING:
+    from collections.abc import Sequence
+
+
+async def reload_jails(
+    socket_path: str,
+    include_jails: Sequence[str] | None = None,
+    exclude_jails: Sequence[str] | None = None,
+) -> None:
+    """Reload fail2ban jails using the shared jail service helper."""
+    await reload_all(
+        socket_path,
+        include_jails=list(include_jails) if include_jails is not None else None,
+        exclude_jails=list(exclude_jails) if exclude_jails is not None else None,
+    )

backend/app/helpers/log_helpers.py

@@ -0,0 +1,21 @@
+"""Shared log-related helpers for service-layer code."""
+
+from __future__ import annotations
+
+from typing import TYPE_CHECKING
+
+from app.services.log_service import preview_log as _preview_log
+from app.services.log_service import test_regex as _test_regex
+
+if TYPE_CHECKING:
+    from app.models.config import LogPreviewRequest, LogPreviewResponse, RegexTestRequest, RegexTestResponse
+
+
+def preview_log(req: LogPreviewRequest) -> LogPreviewResponse:
+    """Return log preview results using the shared log service."""
+    return _preview_log(req)
+
+
+def test_regex(req: RegexTestRequest) -> RegexTestResponse:
+    """Validate a regex pattern using the shared log service."""
+    return _test_regex(req)