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

apps/electron-backend/src/app/api/main.preload.ts

@@ -540,6 +540,9 @@ const electronApi = {
         ipcRenderer.invoke('DB_CLEAR_PLAYLIST_RECENT_ITEMS', playlistId),
     dbRemoveRecentItem: (contentId: number, playlistId: string) =>
         ipcRenderer.invoke('DB_REMOVE_RECENT_ITEM', contentId, playlistId),
+    dbRemoveRecentItemsBatch: (
+        items: { contentId: number; playlistId: string }[]
+    ) => ipcRenderer.invoke('DB_REMOVE_RECENT_ITEMS_BATCH', items),
     dbGetContentByXtreamId: (
         xtreamId: number,
         playlistId: string,

apps/electron-backend/src/app/database/operations/recently-viewed.operations.ts

@@ -150,3 +150,36 @@ export async function removeRecentItem(
 
     return { success: true };
 }
+
+export async function removeRecentItemsBatch(
+    db: AppDatabase,
+    items: { contentId: number; playlistId: string }[]
+): Promise<{ success: boolean; count: number }> {
+    if (!Array.isArray(items) || items.length === 0) {
+        return { success: true, count: 0 };
+    }
+
+    const stmt = db
+        .delete(schema.recentlyViewed)
+        .where(
+            and(
+                eq(
+                    schema.recentlyViewed.contentId,
+                    sql.placeholder('contentId')
+                ),
+                eq(
+                    schema.recentlyViewed.playlistId,
+                    sql.placeholder('playlistId')
+                )
+            )
+        )
+        .prepare();
+
+    await db.transaction(async () => {
+        for (const { contentId, playlistId } of items) {
+            await stmt.execute({ contentId, playlistId });
+        }
+    });
+
+    return { success: true, count: items.length };
+}

apps/electron-backend/src/app/events/database/recently-viewed.events.ts

@@ -35,3 +35,10 @@ handleWorkerRequest(
         playlistId,
     })
 );
+
+handleWorkerRequest(
+    'DB_REMOVE_RECENT_ITEMS_BATCH',
+    (items: { contentId: number; playlistId: string }[]) => ({
+        items,
+    })
+);

apps/electron-backend/src/app/workers/database-worker.types.ts

@@ -39,6 +39,7 @@ export const DB_WORKER_OPERATIONS = [
     'DB_ADD_RECENT_ITEM',
     'DB_CLEAR_PLAYLIST_RECENT_ITEMS',
     'DB_REMOVE_RECENT_ITEM',
+    'DB_REMOVE_RECENT_ITEMS_BATCH',
     'DB_SAVE_PLAYBACK_POSITION',
     'DB_GET_PLAYBACK_POSITION',
     'DB_GET_SERIES_PLAYBACK_POSITIONS',

apps/electron-backend/src/app/workers/database.worker.ts

@@ -73,6 +73,7 @@ import {
     getRecentItems,
     getRecentlyViewed,
     removeRecentItem,
+    removeRecentItemsBatch,
 } from '../database/operations/recently-viewed.operations';
 import {
     deleteXtreamContent,
@@ -761,6 +762,13 @@ async function executeRequest(message: DbWorkerRequestMessage) {
             return removeRecentItem(db, payload.contentId, payload.playlistId);
         }
 
+        case 'DB_REMOVE_RECENT_ITEMS_BATCH': {
+            const payload = message.payload as {
+                items: { contentId: number; playlistId: string }[];
+            };
+            return removeRecentItemsBatch(db, payload.items);
+        }
+
         case 'DB_SAVE_PLAYBACK_POSITION': {
             const payload = message.payload as {
                 playlistId: string;

apps/web/src/typings.d.ts

@@ -273,6 +273,9 @@ declare global {
                 contentId: number,
                 playlistId: string
             ) => Promise<{ success: boolean }>;
+            dbRemoveRecentItemsBatch: (
+                items: { contentId: number; playlistId: string }[]
+            ) => Promise<{ success: boolean; count: number }>;
             dbGetContentByXtreamId: (
                 xtreamId: number,
                 playlistId: string,