Problem:
The "Blocklist & Search" button on download cards fails with a "400 Bad Request (Missing required fields)" when clicked on any television release in Sonarr that represents a full season package or a multi-episode release. 

Root Cause:
1. In `server/services/DownloadMatcher.js`, when a download is matched with a Sonarr queue record, `arrContentId` is populated with `sonarrMatch.episodeId || null`. 
2. However, for multi-episode packs or full season grabs in Sonarr v3, the `episodeId` field is missing from the queue record payload (since the release is associated with multiple episodes). Instead, Sonarr provides an `episodeIds` array. As a result, `arrContentId` is normalized to `null`.
3. When the user clicks the "Blocklist & Search" button in the UI, the frontend calls the `POST /api/dashboard/blocklist-search` endpoint. The request body includes `arrContentId: null`.
4. The backend route validator in `server/routes/dashboard.js` strictly requires all fields including `arrContentId` to be truthy:
   ```javascript
   if (!arrQueueId || !arrType || !arrInstanceUrl || !arrContentId || !arrContentType) {
     return res.status(400).json({ error: 'Missing required fields' });
   }
   ```
   Because `arrContentId` is `null`, this check fails and returns `400 Missing required fields`, completely blocking the blocklist operation (even though queue removal itself does not require an episode ID).
5. Furthermore, the search trigger logic in `dashboard.js` only handles single episode searches via `{ name: 'EpisodeSearch', episodeIds: [arrContentId] }` and has no logic to handle `episodeIds` arrays or fallback searches (such as `SeriesSearch` or `SeasonSearch`).

Proposed Fix:
1. **Relax Backend Validation**: Allow `arrContentId` to be optional or null for `sonarr` queue records to ensure the deletion and blocklist steps can still execute.
2. **Robust Search Triggers**:
   - If `episodeId` is missing but `episodeIds` array is available on the matched record, pass the array of IDs to the frontend/backend.
   - Modify the `dashboard.js` re-search block to support `EpisodeSearch` with multiple IDs, or fall back to triggering a `SeriesSearch` command using the `seriesId` if no specific episode IDs are resolved.