Add extensible notification providers + UI/API

Introduce a provider-based notification system and wire it through the API and admin UI. Added INotificationProvider + notification service implementation and providers (apprise, discord, ntfy, pushover), plus a GET /api/admin/notifications/providers endpoint to expose provider metadata. Refactored code to use provider type strings (removed enum coupling), updated masking/encryption calls, and simplified the test notification endpoint to accept backendId or type+config and call sendToBackend directly.

UI: NotificationsTab now fetches provider metadata and renders provider cards and dynamic config forms (fields driven by provider metadata). Added config field rendering, improved backend cards, and edit/delete actions.

APIs: New providers route, updated admin notification CRUD routes to validate provider types dynamically, updated test route schema. Added download-client categories POST API to fetch categories from clients and wired postImportCategory handling in download-client routes.

Other notable changes: BookDate now fetches Claude models dynamically from Anthropic's Models API; added paginated model fetch helper. Added ALLOW_WEAK_PASSWORD flag exposure to auth providers and password change logic. Doc updates and various tests added/updated. File-organization doc clarifies EPERM fix using stream-based copy.

src/lib/integrations/nzbget.service.ts

@@ -406,6 +406,16 @@ export class NZBGetService implements IDownloadClient {
     }
   }
 
+  /** Not applicable for usenet clients */
+  async getCategories(): Promise<string[]> {
+    return [];
+  }
+
+  /** Not applicable for usenet clients */
+  async setCategory(_id: string, _category: string): Promise<void> {
+    // No-op: post-import category is scoped to torrent clients
+  }
+
   // =========================================================================
   // Category Management
   // =========================================================================

src/lib/integrations/prowlarr.service.ts

@@ -208,6 +208,55 @@ export class ProwlarrService {
     }
   }
 
+  /**
+   * Search with multiple query variations to increase coverage
+   * Fires 2 queries per call: "title author" and "title", then deduplicates by guid
+   */
+  async searchWithVariations(
+    title: string,
+    author: string,
+    filters?: SearchFilters
+  ): Promise<TorrentResult[]> {
+    const queries = [
+      `${title} ${author}`,
+      title,
+    ];
+
+    logger.info(`Searching with ${queries.length} query variations`, { queries });
+
+    const allResults: TorrentResult[] = [];
+
+    for (const query of queries) {
+      try {
+        const results = await this.search(query, filters);
+        logger.info(`Query "${query}" returned ${results.length} results`);
+        allResults.push(...results);
+      } catch (error) {
+        logger.error(`Query "${query}" failed: ${error instanceof Error ? error.message : 'Unknown error'}`);
+        // Continue with other queries even if one fails
+      }
+    }
+
+    const deduplicated = this.deduplicateResults(allResults);
+    logger.info(`Multi-query search: ${allResults.length} total → ${deduplicated.length} after dedup (${allResults.length - deduplicated.length} duplicates removed)`);
+
+    return deduplicated;
+  }
+
+  /**
+   * Deduplicate results by guid, preserving order (first occurrence wins)
+   */
+  private deduplicateResults(results: TorrentResult[]): TorrentResult[] {
+    const seen = new Set<string>();
+    return results.filter(result => {
+      if (seen.has(result.guid)) {
+        return false;
+      }
+      seen.add(result.guid);
+      return true;
+    });
+  }
+
   /**
    * Get list of configured indexers
    */

src/lib/integrations/qbittorrent.service.ts

@@ -729,6 +729,26 @@ export class QBittorrentService implements IDownloadClient {
     }
   }
 
+  /**
+   * Get all configured categories from qBittorrent
+   */
+  async getCategories(): Promise<string[]> {
+    if (!this.cookie) {
+      await this.login();
+    }
+
+    try {
+      const response = await this.client.get('/torrents/categories', {
+        headers: { Cookie: this.cookie },
+      });
+
+      return Object.keys(response.data || {});
+    } catch (error) {
+      logger.error('Failed to get categories', { error: error instanceof Error ? error.message : String(error) });
+      return [];
+    }
+  }
+
   /**
    * Set category for torrent
    */

src/lib/integrations/sabnzbd.service.ts

@@ -825,6 +825,16 @@ export class SABnzbdService implements IDownloadClient {
     await this.archiveCompletedNZB(id);
   }
 
+  /** Not applicable for usenet clients */
+  async getCategories(): Promise<string[]> {
+    return [];
+  }
+
+  /** Not applicable for usenet clients */
+  async setCategory(_id: string, _category: string): Promise<void> {
+    // No-op: post-import category is scoped to torrent clients
+  }
+
   /**
    * Map NZBInfo to the unified DownloadInfo format.
    */

src/lib/integrations/transmission.service.ts

@@ -441,6 +441,29 @@ export class TransmissionService implements IDownloadClient {
     // No-op: torrents are managed by the seeding cleanup scheduler
   }
 
+  /**
+   * Get available categories/labels.
+   * Transmission uses free-form labels — no predefined list to fetch.
+   */
+  async getCategories(): Promise<string[]> {
+    return [];
+  }
+
+  /**
+   * Set the label for a torrent.
+   * Uses the torrent-set RPC method to replace the labels array.
+   */
+  async setCategory(id: string, category: string): Promise<void> {
+    try {
+      const torrent = await this.getTorrentByHash(id);
+      await this.rpc('torrent-set', { ids: [torrent.hashString], labels: [category] });
+      logger.info(`Set label for torrent ${id}: ${category}`);
+    } catch (error) {
+      logger.error('Failed to set label', { error: error instanceof Error ? error.message : String(error) });
+      throw new Error('Failed to set torrent label');
+    }
+  }
+
   // =========================================================================
   // Internal Helpers
   // =========================================================================