Add multi-select support to pmshare panel (#1779)

* Add multi-select support to share panel

- Replace single selection index with per-user selected flag
- Allow sending to multiple selected users
- Add sending state to prevent multiple clicks
- Update default selection logic to mark first user as selected

* 简化代码逻辑

* update

Signed-off-by: bggRGjQaUbCoE <githubaccount56556@proton.me>

---------

Signed-off-by: lesetong <oscarlbw@qq.com>
Co-authored-by: bggRGjQaUbCoE <githubaccount56556@proton.me>

lib/pages/video/reply_new/view.dart

@@ -320,7 +320,7 @@ class _ReplyPageState extends CommonRichTextPubPageState<ReplyPage> {
           item(
             onTap: () async {
               controller.keepChatPanel();
-              ({String title, String url})? res = await Get.to(
+              final ({String title, String url})? res = await Get.to(
                 ReplySearchPage(type: widget.replyType, oid: widget.oid),
               );
               if (res != null) {