fix: correct dragstart cancel method and release claimed filenames after download

- Use dataTransfer.effectAllowed='none' instead of preventDefault() for dragstart
  (preventDefault does not cancel dragstart events per HTML spec)
- Clear claimedFilenames Set in processOneQueueItem finally block to prevent
  stale claims from blocking re-downloads of same VODs

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

src/main.ts

@@ -2895,6 +2895,8 @@ async function processOneQueueItem(item: QueueItem): Promise<void> {
     } finally {
         activeDownloads.delete(item.id);
         cancelledItemIds.delete(item.id);
+        // Release any filenames claimed during this download (prevents stale claims blocking re-downloads)
+        claimedFilenames.clear();
     }
 }
 

src/renderer-queue.ts

@@ -221,7 +221,10 @@ function initQueueDragDrop(): void {
         if (itemId) {
             const item = queue.find(i => i.id === itemId);
             if (!item || item.status !== 'pending') {
-                e.preventDefault();
+                if (e.dataTransfer) {
+                    e.dataTransfer.effectAllowed = 'none';
+                    e.dataTransfer.clearData();
+                }
                 return;
             }
         }