Add RDT-Client support and Prowlarr prompt

Introduce RDT-Client integration and related UI/behavior changes.

- Add RDTClientService extending QBittorrentService with RDT-specific behavior (stale-torrent deletion, postProcess cleanup, no-op categories).
- Register 'rdtclient' in supported client types, display names, and protocol mapping; create RDT client factory in DownloadClientManager.
- Add RDT-Client card to DownloadClientManagement UI and placeholder URL in DownloadClientModal.
- Update qbittorrent service: omit per-torrent savepath/sequential options (favor category/automatic management), make several methods protected, and clean up related comments.
- Make organize-files.processor treat rdtclient as a special-case for cleanup (remove local torrent entries after organize).
- Add prowlarr service singleton invalidation and call it when Prowlarr settings are updated so background jobs pick up new credentials.
- Add confirmation flow when changing Prowlarr URL/API key: new useIndexersSettings logic to detect credential changes, prompt ConfirmModal from IndexersTab, and optionally clear configured indexers on confirmed change.

These changes ensure Real-Debrid-backed qBittorrent-compatible clients are supported correctly and that switching Prowlarr credentials is handled safely.

src/lib/processors/organize-files.processor.ts

@@ -864,8 +864,13 @@ async function cleanupDownloadAfterOrganize(
       removeAfterProcessing: indexer?.removeAfterProcessing ?? 'undefined',
     });
 
-    // Check if this is a non-torrent indexer with cleanup enabled
-    if (!indexer || indexer.protocol?.toLowerCase() === 'torrent' || !indexer.removeAfterProcessing) {
+    // Check if this is a non-torrent indexer with cleanup enabled.
+    // RDT-Client is an exception: even though it's torrent protocol, it needs cleanup
+    // because Real-Debrid handles seeding — local torrent entries should be removed.
+    const isRDTClient = downloadHistory.downloadClient === 'rdtclient';
+    const isTorrentProtocol = indexer?.protocol?.toLowerCase() === 'torrent';
+
+    if (!indexer || (!isRDTClient && isTorrentProtocol) || !indexer.removeAfterProcessing) {
       return;
     }