feat: save repeat audio on mic record and rename button to play repeat

kouyu_english/lib/core/ai_service.dart

@@ -7,7 +7,6 @@ import 'package:http/http.dart' as http;
 
 import 'models.dart';
 import 'generated_content.dart';
-import 'a0_core.dart';
 
 class AiConnectionResult {
   const AiConnectionResult({required this.ok, required this.message});

kouyu_english/lib/core/sherpa_stt_service.dart

@@ -1,5 +1,4 @@
 import 'dart:io';
-import 'dart:typed_data';
 import 'package:flutter/foundation.dart';
 import 'package:flutter/services.dart';
 import 'package:path_provider/path_provider.dart';

kouyu_english/lib/core/voice_service.dart

@@ -1,3 +1,5 @@
+import 'dart:async';
+import 'package:flutter/foundation.dart';
 import 'dart:io';
 
 import 'package:audioplayers/audioplayers.dart';
@@ -16,6 +18,7 @@ class VoiceService {
   final SpeechToText _stt = SpeechToText();
   final AudioRecorder _recorder = AudioRecorder();
   final AudioPlayer _player = AudioPlayer();
+  StreamSubscription<void>? _playerSub;
   bool _speechReady = false;
   bool _ttsInitialized = false;
 
@@ -92,12 +95,23 @@ class VoiceService {
 
   Future<String?> stopRecording() => _recorder.stop();
 
-  Future<void> playRecording(String path) async {
-    await _player.stop();
+  Future<void> playRecording(String path, {VoidCallback? onComplete}) async {
+    await stopRecordingPlayback();
+    if (onComplete != null) {
+      _playerSub = _player.onPlayerComplete.listen((_) {
+        _playerSub?.cancel();
+        _playerSub = null;
+        onComplete();
+      });
+    }
     await _player.play(DeviceFileSource(path));
   }
 
-  Future<void> stopRecordingPlayback() => _player.stop();
+  Future<void> stopRecordingPlayback() async {
+    await _playerSub?.cancel();
+    _playerSub = null;
+    await _player.stop();
+  }
 
   Future<void> deleteRecording(String? path) async {
     if (path == null || path.isEmpty) return;