feat: add multi-channel subscription blocking UI and admin management

- Channel subscription blocking screen with per-channel status display
- Safe URL handling with protocol validation (no open redirect)
- Race-condition-safe subscription check with useRef guard
- Admin channel management page with create, toggle, delete
- Error handlers on all admin mutations with haptic feedback
- Proper type guard for channel subscription error detection
- Accessibility: aria-labels on icon-only buttons
- Localization: en, ru, zh, fa translations

src/api/adminChannels.ts

@@ -0,0 +1,68 @@
+import apiClient from './client';
+
+// Types
+export interface RequiredChannel {
+  id: number;
+  channel_id: string;
+  channel_link: string | null;
+  title: string | null;
+  is_active: boolean;
+  sort_order: number;
+}
+
+export interface ChannelListResponse {
+  items: RequiredChannel[];
+  total: number;
+}
+
+export interface CreateChannelRequest {
+  channel_id: string;
+  channel_link?: string;
+  title?: string;
+}
+
+export interface UpdateChannelRequest {
+  channel_id?: string;
+  channel_link?: string;
+  title?: string;
+  is_active?: boolean;
+  sort_order?: number;
+}
+
+export const adminChannelsApi = {
+  list: async (): Promise<ChannelListResponse> => {
+    const { data } = await apiClient.get<ChannelListResponse>(
+      '/cabinet/admin/channel-subscriptions',
+    );
+    return data;
+  },
+
+  create: async (req: CreateChannelRequest): Promise<RequiredChannel> => {
+    const { data } = await apiClient.post<RequiredChannel>(
+      '/cabinet/admin/channel-subscriptions',
+      req,
+    );
+    return data;
+  },
+
+  update: async (id: number, req: UpdateChannelRequest): Promise<RequiredChannel> => {
+    const { data } = await apiClient.patch<RequiredChannel>(
+      `/cabinet/admin/channel-subscriptions/${id}`,
+      req,
+    );
+    return data;
+  },
+
+  toggle: async (id: number): Promise<RequiredChannel> => {
+    const { data } = await apiClient.post<RequiredChannel>(
+      `/cabinet/admin/channel-subscriptions/${id}/toggle`,
+    );
+    return data;
+  },
+
+  delete: async (id: number): Promise<void> => {
+    await apiClient.delete(`/cabinet/admin/channel-subscriptions/${id}`);
+  },
+};
+
+export default adminChannelsApi;