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/screens/chat/styles.ts

@@ -0,0 +1,102 @@
+import { StyleSheet } from 'react-native';
+import { Spacing, BorderRadius, Theme } from '@/constants/theme';
+
+export const createStyles = (theme: Theme) => {
+  return StyleSheet.create({
+    header: {
+      flexDirection: 'row',
+      justifyContent: 'space-between',
+      alignItems: 'center',
+      paddingHorizontal: Spacing.lg,
+      paddingVertical: Spacing.md,
+      borderBottomWidth: 1,
+      borderBottomColor: theme.border,
+    },
+    headerStatus: {
+      flexDirection: 'row',
+      alignItems: 'center',
+      gap: Spacing.xs,
+    },
+    statusDot: {
+      width: 8,
+      height: 8,
+      borderRadius: 4,
+    },
+    messagesContainer: {
+      flex: 1,
+    },
+    messagesContent: {
+      padding: Spacing.lg,
+      gap: Spacing.md,
+      paddingBottom: Spacing["2xl"],
+    },
+    messageWrapper: {
+      gap: Spacing.xs,
+    },
+    userMessage: {
+      alignItems: 'flex-end',
+    },
+    assistantMessage: {
+      alignItems: 'flex-start',
+    },
+    messageBubble: {
+      maxWidth: '80%',
+      padding: Spacing.md,
+      borderRadius: BorderRadius.lg,
+      shadowColor: theme.primary,
+      shadowOffset: { width: 0, height: 1 },
+      shadowOpacity: 0.1,
+      shadowRadius: 4,
+      elevation: 2,
+    },
+    messageText: {
+      lineHeight: 22,
+    },
+    messageTime: {
+      paddingHorizontal: Spacing.sm,
+    },
+    typingIndicator: {
+      flexDirection: 'row',
+      gap: Spacing.xs,
+      paddingVertical: Spacing.xs,
+    },
+    typingDot: {
+      width: 8,
+      height: 8,
+      borderRadius: 4,
+    },
+    inputContainer: {
+      flexDirection: 'row',
+      alignItems: 'flex-end',
+      gap: Spacing.md,
+      paddingHorizontal: Spacing.lg,
+      paddingVertical: Spacing.md,
+      borderTopWidth: 1,
+      borderTopColor: theme.border,
+    },
+    input: {
+      flex: 1,
+      backgroundColor: theme.backgroundTertiary,
+      borderRadius: BorderRadius.lg,
+      paddingHorizontal: Spacing.lg,
+      paddingVertical: Spacing.md,
+      color: theme.textPrimary,
+      fontSize: 16,
+      maxHeight: 120,
+    },
+    sendButton: {
+      width: 44,
+      height: 44,
+      borderRadius: BorderRadius.lg,
+      backgroundColor: theme.primary,
+      justifyContent: 'center',
+      alignItems: 'center',
+      marginBottom: 2,
+      shadowColor: theme.primary,
+      shadowOffset: { width: 0, height: 2 },
+      shadowOpacity: 0.2,
+      shadowRadius: 8,
+      elevation: 3,
+    },
+  });
+};