fix(分享功能): 添加Markdown转纯文本功能以正确分享内容

在分享会议总结时，原始内容可能包含Markdown格式标记，导致分享的文本包含不必要的格式符号。添加_markdownToPlainText方法移除所有Markdown标记，确保分享的文本是干净的纯文本格式。

lib/modules/meeting/views/bottomSheet/share_bottom_sheet.dart

@@ -128,7 +128,8 @@ class _ShareBottomSheetState extends State<ShareBottomSheet> {
                       onTap: _controller.meetingDetails.value.tasktype >= 3
                           ? () {
                               Get.back();
-                              _copy(_controller.meetingDetails.value.summary);
+                              _copy(_markdownToPlainText(
+                                  _controller.meetingDetails.value.summary));
                             }
                           : null),
                 ]),
@@ -168,8 +169,9 @@ class _ShareBottomSheetState extends State<ShareBottomSheet> {
                                           await getTemporaryDirectory();
                                       final file = File(
                                           '${tempDir.path}/${_controller.meetingData.value.title}_summary.txt');
-                                      await file.writeAsString(_controller
+                                      await file.writeAsString(
-                                          .meetingDetails.value.summary);
+                                          _markdownToPlainText(_controller
+                                              .meetingDetails.value.summary));
                                       _share(file.path,
                                           'exportSummary'.tr); // 对应中文：分享会议总结
                                     } else {
@@ -320,6 +322,63 @@ class _ShareBottomSheetState extends State<ShareBottomSheet> {
     );
   }
 
+  /// 将Markdown格式转换为纯文本
+  String _markdownToPlainText(String markdown) {
+    String text = markdown;
+
+    // 移除粗体标记 **text** 或 __text__
+    text = text.replaceAllMapped(
+        RegExp(r'\*\*(.*?)\*\*'), (match) => match.group(1) ?? '');
+    text = text.replaceAllMapped(
+        RegExp(r'__(.*?)__'), (match) => match.group(1) ?? '');
+
+    // 移除斜体标记 *text* 或 _text_
+    text = text.replaceAllMapped(
+        RegExp(r'\*(.*?)\*'), (match) => match.group(1) ?? '');
+    text = text.replaceAllMapped(
+        RegExp(r'_(.*?)_'), (match) => match.group(1) ?? '');
+
+    // 移除删除线标记 ~~text~~
+    text = text.replaceAllMapped(
+        RegExp(r'~~(.*?)~~'), (match) => match.group(1) ?? '');
+
+    // 移除代码块标记 ```code```
+    text = text.replaceAll(RegExp(r'```[\s\S]*?```'), '');
+
+    // 移除行内代码标记 `code`
+    text = text.replaceAllMapped(
+        RegExp(r'`(.*?)`'), (match) => match.group(1) ?? '');
+
+    // 移除链接标记 [text](url)
+    text = text.replaceAllMapped(
+        RegExp(r'\[([^\]]+)\]\([^\)]+\)'), (match) => match.group(1) ?? '');
+
+    // 移除图片标记 ![alt](url)
+    text = text.replaceAllMapped(
+        RegExp(r'!\[([^\]]*)\]\([^\)]+\)'), (match) => match.group(1) ?? '');
+
+    // 移除标题标记 # ## ### 等
+    text = text.replaceAll(RegExp(r'^#{1,6}\s+', multiLine: true), '');
+
+    // 移除引用标记 >
+    text = text.replaceAll(RegExp(r'^>\s*', multiLine: true), '');
+
+    // 移除列表标记 - * +
+    text = text.replaceAll(RegExp(r'^[\s]*[-\*\+]\s+', multiLine: true), '');
+
+    // 移除有序列表标记 1. 2. 等
+    text = text.replaceAll(RegExp(r'^[\s]*\d+\.\s+', multiLine: true), '');
+
+    // 移除水平分割线
+    text =
+        text.replaceAll(RegExp(r'^[\s]*[-\*_]{3,}[\s]*$', multiLine: true), '');
+
+    // 清理多余的空行
+    text = text.replaceAll(RegExp(r'\n\s*\n\s*\n'), '\n\n');
+
+    return text.trim();
+  }
+
   String _getAllText() {
     String text = '';
     for (var element in _controller.textList) {