修改TTS前的分句和全屏功能

1、TTS前的分句已经可以正常移除图片url了
2、打开full_screen中的全屏后延迟出现“欢迎语”，避免报错
---------
Issue：
1、分句后的文字提交tts，会出现websocket空闲时间过长，导致语音提前结束的情况

lib/screens/full_screen.dart

@@ -67,12 +67,12 @@ class _FullScreenState extends State<FullScreen> {
                       _scrollToBottom();
                     });
                     if (messageService.messages.isEmpty) {
-                      // Future.delayed(const Duration(milliseconds: 500), () {
+                      Future.delayed(const Duration(milliseconds: 500), () {
                         String text = Intl.getCurrentLocale().startsWith('zh')
                             ? "您好，我是众众，请问有什么可以帮您？"
                             : "Hi, I'm Zhongzhong, may I help you ? ";
                         messageService.addMessage(text, false, MessageStatus.normal);
-                      // });
+                      });
                     }
                     return ChatBox(
                       scrollController: _scrollController,

lib/services/chat_sse_service.dart

@@ -35,7 +35,59 @@ class ChatSseService {
       print('初始化用户ID: $_cachedUserId');
     }
     String responseText = '';
-    String tempText = '';
+    StringBuffer buffer = StringBuffer();
+    // 英文分句符
+    final enEnders = RegExp(r'[.!?]');
+    // 中文分句符
+    final zhEnders = RegExp(r'[。！？]');
+    // 专有名词保护
+    String protectIDUNYX(String text) => text.replaceAll('ID.UNYX', 'ID_UNYX');
+    String restoreIDUNYX(String text) => text.replaceAll('ID_UNYX', 'ID.UNYX');
+    Future<void> processBuffer(bool isChinese) async {
+      String txt = buffer.toString();
+      // 先过滤 markdown 图片语法
+      int imgStart = txt.indexOf('![');
+      while (imgStart != -1) {
+        int imgEnd = txt.indexOf(')', imgStart);
+        if (imgEnd == -1) {
+          // 图片语法未闭合，缓存剩余部分
+          buffer.clear();
+          buffer.write(txt.substring(imgStart));
+          return;
+        }
+        // 移除图片语法
+        txt = txt.substring(0, imgStart) + txt.substring(imgEnd + 1);
+        imgStart = txt.indexOf('![');
+      }
+      // 彻底移除 markdown 有序/无序列表序号（如 1.、2.、-、*、+）
+      txt = txt.replaceAll(RegExp(r'(^|\n)[ \t]*[0-9]+\.[ \t]*'), '\n');
+      txt = txt.replaceAll(RegExp(r'(^|\n)[ \t]*[-\*\+][ \t]+'), '\n');
+      // 分句符
+      RegExp enders = isChinese ? zhEnders : enEnders;
+      int lastEnd = 0;
+      // 本地缓存句子
+      List<String> sentences = [];
+      for (final match in enders.allMatches(txt)) {
+        int endIndex = match.end;
+        String sentence = txt.substring(lastEnd, endIndex).trim();
+        if (sentence.isNotEmpty) {
+          sentences.add(sentence);
+        }
+        lastEnd = endIndex;
+      }
+      // 只在达到完整句子时调用 TtsUtil.send
+      for (final s in sentences) {
+        String ttsStr=CommonUtil.cleanText(s, true);
+        // print("发送数据到TTS: $ttsStr");
+        TtsUtil.send(ttsStr);
+      }
+      // 缓存剩余不完整部分
+      String remain = txt.substring(lastEnd).trim();
+      buffer.clear();
+      if (remain.isNotEmpty) {
+        buffer.write(remain);
+      }
+    }
     _currentClient = HttpClient();
     try {
       final chatUri = Uri.parse('http://143.64.185.20:18606/chat');
@@ -62,7 +114,7 @@ class ChatSseService {
           if (line.startsWith('data:')) {
             final jsonStr = line.substring(5).trim();
             if (jsonStr == '[DONE]' || jsonStr.contains('message_end')) {
-              TtsUtil.complete();
+              await processBuffer(isChinese);
               onStreamResponse(messageId, responseText, true);
               break;
             }
@@ -74,27 +126,12 @@ class ChatSseService {
               }
               if (jsonData['event'].toString().contains('message')) {
                 final textChunk =
-                    jsonData.containsKey('answer') ? jsonData['answer'] : '';
+                jsonData.containsKey('answer') ? jsonData['answer'] : '';
                 if (_isAborted) {
                   break;
                 }
-                tempText += textChunk;
-                if (tempText.contains("ID.")) {
-                  tempText = tempText.replaceAllMapped(
-                      RegExp(r'ID\.', caseSensitive: false), (m) => 'ID ');
-                }
-                int endIndex = _getCompleteTextEndIndex(tempText);
-                String completeText =  CommonUtil.cleanText(tempText.substring(0, endIndex).trim(), true);
-                if (completeText.isNotEmpty) {
-                  if (_isFirstData && _startTtsFuture != null) {
-                    await _startTtsFuture;
-                    _isFirstData = false;
-                  }
-                  completeText += isChinese ? '，' : ',';
-                  print("----------------------Send text: " + completeText);
-                  TtsUtil.send(completeText);
-                }
-                tempText = tempText.substring(endIndex).trim();
+                buffer.write(textChunk);
+                await processBuffer(isChinese);
                 responseText += textChunk;
                 onStreamResponse(messageId, responseText, false);
               }
@@ -109,7 +146,6 @@ class ChatSseService {
     } catch (e) {
       // todo
     } finally {
-      print("------------------------------finally");
       resetRequest();
     }
   }