Initial commit: 健康管家 AI 健康陪伴助手

- Backend: .NET 10 Minimal API + EF Core + PostgreSQL
- Frontend: Flutter + Riverpod + GoRouter + Dio
- AI: DeepSeek LLM + Qwen VLM (OpenAI-compatible)
- Auth: SMS + JWT (access/refresh tokens)
- Features: AI chat, health tracking, medication management, diet analysis, exercise plans, doctor consultations, report analysis

health_app/lib/utils/sse_handler.dart

@@ -0,0 +1,84 @@
+import 'dart:async';
+import 'dart:convert';
+import 'package:dio/dio.dart';
+import '../core/api_client.dart';
+
+/// 跨平台 SSE 流处理（基于 Dio 流式响应，支持 Android/iOS/Web）
+class SseHandler {
+  /// 连接 SSE 端点，返回事件流
+  static Stream<Map<String, dynamic>> connect({
+    required String agentType,
+    required String message,
+    String? conversationId,
+    required String token,
+  }) {
+    final params = <String, String>{
+      'message': message,
+      'token': token,
+    };
+    if (conversationId != null) {
+      params['conversationId'] = conversationId;
+    }
+    final query = params.entries
+        .map((e) => '${e.key}=${Uri.encodeComponent(e.value)}')
+        .join('&');
+    final url = '$baseUrl/api/ai/$agentType/chat?$query';
+
+    final controller = StreamController<Map<String, dynamic>>();
+    _connect(controller, url);
+    return controller.stream;
+  }
+
+  static Future<void> _connect(
+    StreamController<Map<String, dynamic>> controller,
+    String url,
+  ) async {
+    try {
+      final dio = Dio(BaseOptions(
+        connectTimeout: const Duration(seconds: 15),
+        receiveTimeout: const Duration(minutes: 5),
+      ));
+
+      final response = await dio.get(
+        url,
+        options: Options(responseType: ResponseType.stream),
+      );
+
+      final stream = response.data.stream as Stream<List<int>>;
+      var buffer = '';
+
+      await for (final chunk in stream) {
+        if (controller.isClosed) break;
+        final text = utf8.decode(chunk, allowMalformed: true);
+        buffer += text;
+
+        // 按行解析 SSE 数据
+        while (buffer.contains('\n')) {
+          final newlineIdx = buffer.indexOf('\n');
+          var line = buffer.substring(0, newlineIdx).trim();
+          buffer = buffer.substring(newlineIdx + 1);
+
+          if (line.isEmpty || !line.startsWith('data: ')) continue;
+          final data = line.substring(6);
+
+          if (data == '[DONE]') {
+            controller.close();
+            return;
+          }
+
+          try {
+            controller.add(jsonDecode(data) as Map<String, dynamic>);
+          } catch (_) {
+            // 跳过无法解析的行
+          }
+        }
+      }
+      controller.close();
+    } catch (e) {
+      if (!controller.isClosed) {
+        controller.add({'action': 'error', 'message': e.toString()});
+        controller.close();
+      }
+    }
+  }
+}