Function UploadPanel 

pub(crate) fn UploadPanel(props: UploadPanelProps) -> impl IntoView

上传面板主体：children（拖放区）在上，逐文件状态列表在下。

图鉴预览与 AssetUploadModal 共用：列表数据由调用方以信号提供，重试 / 移除经回调上抛。

Required Props

• items: impl Into<Signal<Vec<UploadItem>>>
• on_retry: impl Into<Callback<u64>>
• on_remove: impl Into<Callback<u64>>
• children: [Children]