feat(voice): add VoiceApi and VoiceStatus model

lib/data/api/voice_api.dart

@@ -0,0 +1,81 @@
+import 'dart:typed_data';
+
+import 'package:dio/dio.dart';
+
+import 'api_client.dart';
+
+class VoiceStatus {
+  final bool enabled;
+  final bool stt;
+  final bool tts;
+
+  const VoiceStatus({
+    required this.enabled,
+    required this.stt,
+    required this.tts,
+  });
+
+  /// True only when voice is enabled AND both STT and TTS are ready.
+  bool get fullyAvailable => enabled && stt && tts;
+
+  factory VoiceStatus.fromJson(Map<String, dynamic> json) => VoiceStatus(
+        enabled: json['enabled'] as bool? ?? false,
+        stt: json['stt'] as bool? ?? false,
+        tts: json['tts'] as bool? ?? false,
+      );
+}
+
+class VoiceApi {
+  final Dio _dio;
+  const VoiceApi(this._dio);
+
+  /// Check whether voice features are available on this server.
+  Future<VoiceStatus> checkStatus() async {
+    try {
+      final response = await _dio.get('/api/voice/status');
+      return VoiceStatus.fromJson(response.data as Map<String, dynamic>);
+    } on DioException catch (e) {
+      throw dioToApp(e);
+    }
+  }
+
+  /// POST WebM/Opus audio bytes and return the transcript string.
+  /// Returns empty string on empty or error response.
+  Future<String> transcribe(Uint8List audioBytes) async {
+    try {
+      final formData = FormData.fromMap({
+        'audio': MultipartFile.fromBytes(
+          audioBytes,
+          filename: 'audio.webm',
+          contentType: DioMediaType('audio', 'webm'),
+        ),
+      });
+      final response = await _dio.post(
+        '/api/voice/transcribe',
+        data: formData,
+        options: Options(
+          receiveTimeout: const Duration(seconds: 60),
+          contentType: 'multipart/form-data',
+        ),
+      );
+      final data = response.data as Map<String, dynamic>;
+      return (data['transcript'] as String? ?? '').trim();
+    } on DioException catch (e) {
+      throw dioToApp(e);
+    }
+  }
+
+  /// POST text and return raw WAV bytes.
+  Future<Uint8List> synthesise(String text) async {
+    try {
+      final response = await _dio.post(
+        '/api/voice/synthesise',
+        data: {'text': text},
+        options: Options(responseType: ResponseType.bytes),
+      );
+      return Uint8List.fromList(response.data as List<int>);
+    } on DioException catch (e) {
+      throw dioToApp(e);
+    }
+  }
+}

test/widget_test.dart

@@ -1,3 +1,4 @@
+import 'package:fabled_app/data/api/voice_api.dart';
 import 'package:fabled_app/data/models/knowledge_item.dart';
 import 'package:fabled_app/data/models/note.dart';
 import 'package:flutter_test/flutter_test.dart';
@@ -66,4 +67,35 @@ void main() {
       expect(item.status, isNull);
     });
   });
+
+  group('VoiceStatus.fromJson', () {
+    test('parses enabled with stt and tts available', () {
+      final status = VoiceStatus.fromJson({
+        'enabled': true,
+        'stt': true,
+        'tts': true,
+      });
+      expect(status.enabled, isTrue);
+      expect(status.stt, isTrue);
+      expect(status.tts, isTrue);
+    });
+
+    test('parses disabled state', () {
+      final status = VoiceStatus.fromJson({
+        'enabled': false,
+        'stt': false,
+        'tts': false,
+      });
+      expect(status.enabled, isFalse);
+    });
+
+    test('fullyAvailable is false when enabled but stt is false', () {
+      final status = VoiceStatus.fromJson({
+        'enabled': true,
+        'stt': false,
+        'tts': true,
+      });
+      expect(status.fullyAvailable, isFalse);
+    });
+  });
 }