feat(merge-split): integrate merge-group pipeline into processQueue and cleanup handlers

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/main.ts

@@ -3258,7 +3258,11 @@ async function processQueue(): Promise<void> {
         for (let attempt = 1; attempt <= maxAttempts; attempt++) {
             appendDebugLog('queue-item-attempt', { itemId: item.id, attempt, max: maxAttempts });
 
-            const result = await downloadVOD(item, (progress) => {
+            const result = item.mergeGroup
+                ? await processDownloadMergeGroup(item, (progress) => {
+                    mainWindow?.webContents.send('download-progress', progress);
+                })
+                : await downloadVOD(item, (progress) => {
                     mainWindow?.webContents.send('download-progress', progress);
                 });
 
@@ -3784,6 +3788,18 @@ ipcMain.handle('remove-from-queue', (_, id: string) => {
         appendDebugLog('queue-item-removed-active-cancelled', { id });
     }
 
+    // Clean up merge-group temp files (must run for any merge group, not just active)
+    const removedItem = downloadQueue.find(item => item.id === id);
+    if (removedItem?.mergeGroup) {
+        const mg = removedItem.mergeGroup;
+        for (const key of Object.keys(mg.downloadedFiles)) {
+            try { if (fs.existsSync(mg.downloadedFiles[Number(key)])) fs.unlinkSync(mg.downloadedFiles[Number(key)]); } catch { }
+        }
+        if (mg.mergedFile) {
+            try { if (fs.existsSync(mg.mergedFile)) fs.unlinkSync(mg.mergedFile); } catch { }
+        }
+    }
+
     downloadQueue = downloadQueue.filter(item => item.id !== id);
     saveQueue(downloadQueue);
     emitQueueUpdated();