added remove all item from queue

src/server/services/download_service.py

@@ -600,6 +600,34 @@ class DownloadService:
         
         return count
 
+    async def clear_pending(self) -> int:
+        """Clear all pending downloads from the queue.
+
+        Returns:
+            Number of items cleared
+        """
+        count = len(self._pending_queue)
+        self._pending_queue.clear()
+        self._pending_items_by_id.clear()
+        logger.info("Cleared pending items", count=count)
+        
+        # Save queue state
+        self._save_queue()
+        
+        # Broadcast queue status update
+        if count > 0:
+            queue_status = await self.get_queue_status()
+            await self._broadcast_update(
+                "queue_status",
+                {
+                    "action": "pending_cleared",
+                    "cleared_count": count,
+                    "queue_status": queue_status.model_dump(mode="json"),
+                },
+            )
+        
+        return count
+
     async def retry_failed(
         self, item_ids: Optional[List[str]] = None
     ) -> List[str]: