Fix critical bugs in speech recognition system

1. Add finalResult property to SpeechRecognitionResult class
   - Distinguish between real-time and final recognition results
   - Update factory methods, toString, equals, and hashCode
   - Update toMap and fromMap methods

2. Update YxAsrService to support finalResult flag
   - Add finalResult parameter to _sendResult method
   - Mark final results with finalResult: true
   - Keep real-time results as finalResult: false (default)

3. Remove unused methods to clean up codebase
   - Remove unused _toggleRecording method
   - Remove unused _updateTextController method
   - Clean up orphaned comments

These fixes resolve linter errors and ensure proper text appending functionality.

example/lib/main.dart

@@ -160,72 +160,6 @@ class _SpeechRecognitionPageState extends State<SpeechRecognitionPage> {
     });
   }
 
-  /// 更新文本控制器内容
-  void _updateTextController() {
-    // 组合已确认的结果和当前实时结果
-    final confirmedText = _realtimeResults.join(' ');
-    final displayText = _currentText.isNotEmpty
-        ? '$confirmedText ${_currentText}'.trim()
-        : confirmedText;
-
-    // 只有当内容真正改变时才更新，避免光标跳动
-    if (_textController.text != displayText) {
-      final cursorPosition = _textController.selection.baseOffset;
-      _textController.text = displayText;
-
-      // 尝试保持光标位置，如果超出范围则移到末尾
-      if (cursorPosition <= displayText.length) {
-        _textController.selection = TextSelection.fromPosition(
-          TextPosition(offset: cursorPosition),
-        );
-      } else {
-        _textController.selection = TextSelection.fromPosition(
-          TextPosition(offset: displayText.length),
-        );
-      }
-    }
-  }
-
-  /// 切换录音状态
-  Future<void> _toggleRecording() async {
-    if (!_isInitialized) return;
-
-    try {
-      if (_isListening) {
-        print('📱 [Example] 停止录音');
-        await _speechService.stopListening();
-
-        // 录音结束后，将当前识别的文本保存到历史记录
-        if (_currentText.isNotEmpty) {
-          setState(() {
-            _realtimeResults.add(_currentText);
-            _recognitionHistory.insert(0, _currentText);
-            print('📱 [Example] 添加到历史记录: $_currentText');
-            // 保持历史记录在合理数量
-            if (_recognitionHistory.length > 10) {
-              _recognitionHistory.removeLast();
-            }
-            // 清空当前文本
-            _currentText = '';
-            _updateTextController();
-          });
-        }
-      } else {
-        print('📱 [Example] 开始录音');
-        // 清空之前的结果，开始新的录音
-        setState(() {
-          _realtimeResults.clear();
-          _currentText = '';
-          _textController.clear();
-        });
-        await _speechService.startListening(partialResults: true);
-      }
-    } catch (e) {
-      print('📱 [Example] 录音操作失败: $e');
-      _showErrorSnackBar('录音操作失败: $e');
-    }
-  }
-
   @override
   Widget build(BuildContext context) {
     return Scaffold(

lib/src/models/speech_recognition_result.dart

@@ -9,10 +9,14 @@ class SpeechRecognitionResult {
   /// 备选识别结果
   final List<String> alternatives;
 
+  /// 是否为最终结果（true: 最终结果, false: 实时结果）
+  final bool finalResult;
+
   const SpeechRecognitionResult({
     required this.recognizedWords,
     this.confidence = 0.0,
     this.alternatives = const [],
+    this.finalResult = false,
   });
 
   /// 从 Map 创建 [SpeechRecognitionResult] 实例
@@ -21,6 +25,7 @@ class SpeechRecognitionResult {
       recognizedWords: map['recognizedWords'] as String? ?? '',
       confidence: (map['confidence'] as num?)?.toDouble() ?? 0.0,
       alternatives: List<String>.from(map['alternatives'] as List? ?? []),
+      finalResult: map['finalResult'] as bool? ?? false,
     );
   }
 
@@ -30,13 +35,14 @@ class SpeechRecognitionResult {
       'recognizedWords': recognizedWords,
       'confidence': confidence,
       'alternatives': alternatives,
+      'finalResult': finalResult,
     };
   }
 
   @override
   String toString() {
     return 'SpeechRecognitionResult(recognizedWords: $recognizedWords, '
-        'confidence: $confidence, alternatives: $alternatives)';
+        'confidence: $confidence, alternatives: $alternatives, finalResult: $finalResult)';
   }
 
   @override
@@ -45,6 +51,7 @@ class SpeechRecognitionResult {
     return other is SpeechRecognitionResult &&
         other.recognizedWords == recognizedWords &&
         other.confidence == confidence &&
+        other.finalResult == finalResult &&
         other.alternatives.length == alternatives.length &&
         other.alternatives.every((alt) => alternatives.contains(alt));
   }
@@ -53,6 +60,7 @@ class SpeechRecognitionResult {
   int get hashCode {
     return recognizedWords.hashCode ^
         confidence.hashCode ^
+        finalResult.hashCode ^
         alternatives.hashCode;
   }
 }

lib/src/yx_asr_service.dart

@@ -586,6 +586,7 @@ class YxAsrService implements SpeechRecognitionService {
               recognizedWords: result.text,
               confidence: 1.0,
               alternatives: [],
+              finalResult: true, // 标记为最终结果
             );
           } else {
             debugPrint('⚠️ [YxAsr] 流式最终结果为空');
@@ -785,12 +786,14 @@ class YxAsrService implements SpeechRecognitionService {
     required String recognizedWords,
     required double confidence,
     required List<String> alternatives,
+    bool finalResult = false,
   }) {
     debugPrint('📤 [YxAsr] 发送识别结果: "$recognizedWords"');
     final result = SpeechRecognitionResult(
       recognizedWords: recognizedWords,
       confidence: confidence,
       alternatives: alternatives,
+      finalResult: finalResult,
     );
     _resultController.add(result);
   }