Admin requests: paginated API & UI overhaul

Add a paginated Admin Requests API and fully refactor the admin requests UI to support filtering, sorting, pagination, and URL state.

- New API: src/app/api/admin/requests/route.ts implements paginated, searchable, filterable, and sortable request listing with proper relation includes and pagination metadata.
- Frontend: RecentRequestsTable rewritten to fetch via SWR (authenticatedFetcher), read/write URL query params, debounce search, support status/user filters, sortable columns, page size selector, and full pagination UI; added loading/error states and toast feedback for actions.
- Admin page updated to use Suspense and the new RecentRequestsTable (component now fetches its own data).
- Settings: deprecated single download-client PUT route now maps updates into the new multi-client format (download_clients JSON), logs deprecation, and invalidates download client manager; settings GET now reads multi-client config for backward compatibility.
- Processors: monitor-download and retry-failed-imports updated to use the download-client-manager and new PathMappingConfig shape for path mapping logic.
- Minor API/schema updates: request-with-torrent schema extended (indexerId, infoUrl, protocol) and setup complete no longer writes legacy path keys.
- Tests updated to reflect API and processor changes.

This change centralizes request management on the server, modernizes the UI for large datasets, and migrates download client settings toward a multi-client configuration while keeping backward compatibility.

tests/processors/monitor-download.processor.test.ts

@@ -19,6 +19,9 @@ const sabMock = vi.hoisted(() => ({
 const configMock = vi.hoisted(() => ({
   getMany: vi.fn(),
 }));
+const downloadClientManagerMock = vi.hoisted(() => ({
+  getClientForProtocol: vi.fn(),
+}));
 
 vi.mock('@/lib/db', () => ({
   prisma: prismaMock,
@@ -40,6 +43,10 @@ vi.mock('@/lib/services/config.service', () => ({
   getConfigService: () => configMock,
 }));
 
+vi.mock('@/lib/services/download-client-manager.service', () => ({
+  getDownloadClientManager: () => downloadClientManagerMock,
+}));
+
 describe('processMonitorDownload', () => {
   beforeEach(() => {
     vi.clearAllMocks();
@@ -57,10 +64,14 @@ describe('processMonitorDownload', () => {
       speed: 0,
       eta: 0,
     });
-    configMock.getMany.mockResolvedValue({
-      download_client_remote_path_mapping_enabled: 'true',
-      download_client_remote_path: '/remote/done',
-      download_client_local_path: '/downloads',
+    downloadClientManagerMock.getClientForProtocol.mockResolvedValue({
+      id: 'client-1',
+      type: 'qbittorrent',
+      name: 'qBittorrent',
+      enabled: true,
+      remotePathMappingEnabled: true,
+      remotePath: '/remote/done',
+      localPath: '/downloads',
     });
     prismaMock.request.update.mockResolvedValue({});
     prismaMock.downloadHistory.update.mockResolvedValue({});
@@ -161,10 +172,12 @@ describe('processMonitorDownload', () => {
       timeLeft: 0,
       downloadPath: '/usenet/complete/Book',
     });
-    configMock.getMany.mockResolvedValue({
-      download_client_remote_path_mapping_enabled: 'false',
-      download_client_remote_path: '',
-      download_client_local_path: '',
+    downloadClientManagerMock.getClientForProtocol.mockResolvedValue({
+      id: 'client-2',
+      type: 'sabnzbd',
+      name: 'SABnzbd',
+      enabled: true,
+      remotePathMappingEnabled: false,
     });
     prismaMock.request.update.mockResolvedValue({});
     prismaMock.downloadHistory.update.mockResolvedValue({});