feat: add community enhancements — password reset, audit logs, multi-source backup

Three community-requested features:

1. CLI password reset: `backupx reset-password --username admin --password xxx`
   Docker users can run via `docker exec`. No full app init needed.

2. Audit logging: async fire-and-forget audit trail for all key operations
   (login, CRUD on tasks/targets/records, settings changes).
   New UI page at /audit with category filter and pagination.

3. Multi-source path backup: file backup tasks now support multiple source
   directories packed into a single tar archive. Backward compatible with
   existing single sourcePath field.

web/src/services/audit.ts

@@ -0,0 +1,7 @@
+import { http } from './http'
+import type { AuditLogListResult } from '../types/audit'
+
+export async function listAuditLogs(params: { category?: string; limit?: number; offset?: number }) {
+  const response = await http.get<{ code: string; message: string; data: AuditLogListResult }>('/audit-logs', { params })
+  return response.data.data
+}