feat: 实现减脂体重管理App完整功能

- 实现拍照识别食物功能（集成大语言模型视觉能力）
- 实现智能对话功能（集成大语言模型流式输出）
- 实现食物记录和卡路里管理功能
- 实现体重记录和统计功能
- 实现健康数据管理页面
- 配置数据库表结构（用户、食物记录、体重记录）
- 实现Express后端API路由
- 配置Tab导航和前端页面
- 采用健康运动配色方案

client/metro.config.js

@@ -0,0 +1,121 @@
+const { getDefaultConfig } = require('expo/metro-config');
+const { createProxyMiddleware } = require('http-proxy-middleware');
+const connect = require('connect');
+
+const config = getDefaultConfig(__dirname);
+
+// 安全地获取 Expo 的默认排除列表
+const existingBlockList = [].concat(config.resolver.blockList || []);
+
+config.resolver.blockList = [
+  ...existingBlockList,
+  /.*\/\.expo\/.*/, // Expo 的缓存和构建产物目录
+
+  // 1. 原生代码 (Java/C++/Objective-C)
+  /.*\/react-native\/ReactAndroid\/.*/,
+  /.*\/react-native\/ReactCommon\/.*/,
+
+  // 2. 纯开发和调试工具
+  // 这些工具只在开发电脑上运行，不会被打包到应用中
+  /.*\/@typescript-eslint\/eslint-plugin\/.*/,
+
+  // 3. 构建时数据
+  // 这个数据库只在打包过程中使用，应用运行时不需要
+  /.*\/caniuse-lite\/data\/.*/,
+
+  // 4. 通用规则
+  /.*\/__tests__\/.*/, // 排除所有测试目录
+  /.*\.git\/.*/, // 排除 Git 目录
+];
+
+const BACKEND_TARGET = 'http://localhost:9091';
+
+const apiProxy = createProxyMiddleware({
+  target: BACKEND_TARGET,
+  changeOrigin: true,
+  logLevel: 'debug',
+  proxyTimeout: 86400000,
+  onProxyReq: (proxyReq, req) => {
+    const accept = req.headers.accept || '';
+    if (accept.includes('text/event-stream')) {
+      proxyReq.setHeader('accept-encoding', 'identity');
+    }
+  },
+  onProxyRes: (proxyRes, req, res) => {
+    const contentType = proxyRes.headers['content-type'] || '';
+    if (contentType.includes('text/event-stream') || contentType.includes('application/stream')) {
+      res.setHeader('Cache-Control', 'no-cache');
+      res.setHeader('Connection', 'keep-alive');
+      res.setHeader('X-Accel-Buffering', 'no');
+      if (typeof res.flushHeaders === 'function') {
+        try { res.flushHeaders(); } catch {}
+      }
+    }
+  },
+});
+
+const streamProxy = createProxyMiddleware({
+  target: BACKEND_TARGET,
+  changeOrigin: true,
+  logLevel: 'debug',
+  ws: true,
+  proxyTimeout: 86400000,
+  onProxyReq: (proxyReq, req) => {
+    const upgrade = req.headers.upgrade;
+    const accept = req.headers.accept || '';
+    if (upgrade && upgrade.toLowerCase() === 'websocket') {
+      proxyReq.setHeader('Connection', 'upgrade');
+      proxyReq.setHeader('Upgrade', req.headers.upgrade);
+    } else if (accept.includes('text/event-stream')) {
+      proxyReq.setHeader('accept-encoding', 'identity');
+      proxyReq.setHeader('Connection', 'keep-alive');
+    }
+  },
+  onProxyRes: (proxyRes, req, res) => {
+    const contentType = proxyRes.headers['content-type'] || '';
+    if (contentType.includes('text/event-stream') || contentType.includes('application/stream')) {
+      res.setHeader('Cache-Control', 'no-cache');
+      res.setHeader('Connection', 'keep-alive');
+      res.setHeader('X-Accel-Buffering', 'no');
+      if (typeof res.flushHeaders === 'function') {
+        try { res.flushHeaders(); } catch {}
+      }
+    }
+  },
+});
+
+const shouldProxyToBackend = (url) => {
+  if (!url) return false;
+  if (/^\/api\/v\d+\//.test(url)) {
+    return true;
+  }
+  return false;
+};
+
+const isWebSocketRequest = (req) =>
+  !!(req.headers.upgrade && req.headers.upgrade.toLowerCase() === 'websocket');
+const isSSERequest = (req) => {
+  const accept = req.headers.accept || '';
+  return accept.includes('text/event-stream');
+};
+
+config.server = {
+  ...config.server,
+  enhanceMiddleware: (metroMiddleware, metroServer) => {
+    return connect()
+      .use((req, res, next) => {
+        if (shouldProxyToBackend(req.url)) {
+          console.log(`[Metro Proxy] Forwarding ${req.method} ${req.url}`);
+
+          if (isWebSocketRequest(req) || isSSERequest(req)) {
+            return streamProxy(req, res, next);
+          }
+          return apiProxy(req, res, next);
+        }
+        next();
+      })
+      .use(metroMiddleware);
+  },
+};
+
+module.exports = config;