Add admin maintenance endpoints and file deletion functionality

- Introduced a new `/api/admin/maintenance` route for administrative maintenance tasks, requiring admin authorization.
- Implemented the `DeleteAsync` method in `IFileStorage` to allow for the deletion of files associated with closed support tickets.
- Updated API documentation to include details about the new maintenance operations and their effects on closed tickets.
- Enhanced frontend routing to include the new maintenance section in the admin panel, improving navigation for administrators.
- Added localization support for maintenance-related actions in both Russian and English.

frontend/src/shared/api/types.ts

@@ -270,6 +270,10 @@ export type TicketSummaryDto = {
   messagePreview: string | null
 }
 
+export type DeleteClosedTicketsResponseDto = {
+  deletedCount: number
+}
+
 export type TicketDetailDto = {
   id: string
   userId: string

frontend/src/shared/lib/i18n.ts

@@ -196,8 +196,9 @@ const resources = {
           nodes: 'Ноды',
           apps: 'Приложения',
           news: 'Новости',
-          support: 'Поддержка',
+          support: 'Тикеты',
           audit: 'Аудит',
+          maintenance: 'Обслуживание',
         },
         users: {
           searchPlaceholder: 'Поиск по имени пользователя',
@@ -345,6 +346,15 @@ const resources = {
           source: 'Источник',
           empty: 'Журнал аудита пуст.',
         },
+        maintenance: {
+          closedTickets: {
+            title: 'Закрытые обращения',
+            description: 'Удалить все закрытые обращения вместе с перепиской и вложениями (файлами). Действие необратимо.',
+            action: 'Удалить закрытые обращения',
+            confirm: 'Удалить все закрытые обращения и файлы в них? Действие необратимо.',
+            deleted: 'Удалено обращений: {{count}}.',
+          },
+        },
         stats: {
           totalUsers: 'Всего пользователей',
           activatedUsers: 'Активировано',
@@ -552,8 +562,9 @@ const resources = {
           nodes: 'Nodes',
           apps: 'Apps',
           news: 'News',
-          support: 'Support',
+          support: 'Tickets',
           audit: 'Audit',
+          maintenance: 'Maintenance',
         },
         users: {
           searchPlaceholder: 'Search by username',
@@ -701,6 +712,15 @@ const resources = {
           source: 'Source',
           empty: 'The audit log is empty.',
         },
+        maintenance: {
+          closedTickets: {
+            title: 'Closed tickets',
+            description: 'Delete all closed tickets along with their comments and attachments (files). This cannot be undone.',
+            action: 'Delete closed tickets',
+            confirm: 'Delete all closed tickets and their files? This cannot be undone.',
+            deleted: 'Deleted tickets: {{count}}.',
+          },
+        },
         stats: {
           totalUsers: 'Total users',
           activatedUsers: 'Activated',