perf(recents): batch Xtream remove-recent-item into a single IPC call

Clearing all recents of a given content type fired N concurrent IPC calls,
each opening its own implicit transaction in the recently_viewed table.
For users with hundreds of recently-watched VOD/series rows this added
real overhead even though the UI updates optimistically.

Add a new DB_REMOVE_RECENT_ITEMS_BATCH path end-to-end:
- removeRecentItemsBatch() Drizzle op: one transaction, one prepared
  statement reused per row
- Wire through worker → IPC handler → preload → window.electron typings
  → DatabaseService
- UnifiedRecentDataService.removeRecentItemsBatch() groups items by
  source. Xtream items go through the new batch IPC. M3U/Stalker items
  still go per-playlist because they update a JSON column on the
  playlist row, not the recently_viewed table — but they now run in
  parallel with the Xtream batch via a single Promise.all.
- Single call site updated: unified-collection-page "Clear all of type"
  confirmation handler.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
Entire-Checkpoint: 4bfb62f988b7

libs/services/src/lib/database-electron.service.ts

@@ -838,6 +838,21 @@ export class DatabaseService {
         }
     }
 
+    async removeRecentItemsBatch(
+        items: { contentId: number; playlistId: string }[]
+    ): Promise<boolean> {
+        if (items.length === 0) {
+            return true;
+        }
+        try {
+            await window.electron.dbRemoveRecentItemsBatch(items);
+            return true;
+        } catch (error) {
+            console.error('Error removing recent items batch:', error);
+            return false;
+        }
+    }
+
     /**
      * Get content by xtream ID
      */