feat: add download button to Tables/Images views, add task history delete/clear-all

web/backend/routers/tasks.py

@@ -112,6 +112,29 @@ async def get_task(
     return task
 
 
+@router.delete("/{task_id}")
+async def delete_task(
+    task_id: str,
+    current_user: dict = Depends(get_current_user),
+):
+    """Delete a single task by ID."""
+    loop = asyncio.get_event_loop()
+    deleted = await loop.run_in_executor(None, lambda: db_schema.delete_task(task_id))
+    if not deleted:
+        raise HTTPException(status_code=404, detail="任务不存在")
+    return {"message": "已删除"}
+
+
+@router.delete("")
+async def clear_all_tasks(
+    current_user: dict = Depends(get_current_user),
+):
+    """Clear all task history records."""
+    loop = asyncio.get_event_loop()
+    count = await loop.run_in_executor(None, db_schema.clear_task_history)
+    return {"message": f"已清除 {count} 条记录", "count": count}
+
+
 @router.post("/{task_id}/retry")
 async def retry_task(
     task_id: str,