feat: 添加相机和相册权限请求功能

- 在 AI 体态评估页面中集成相机和相册权限请求逻辑
- 更新 app.json 和 Info.plist，添加相应的权限说明
- 修改布局以支持照片上传功能，用户可上传正面、侧面和背面照片
- 更新 package.json 和 package-lock.json，添加 expo-image-picker 依赖

app/(tabs)/_layout.tsx

@@ -4,9 +4,13 @@ import React from 'react';
 import { Text, TouchableOpacity, View } from 'react-native';
 
 import { IconSymbol } from '@/components/ui/IconSymbol';
+import { Colors } from '@/constants/Colors';
 import { TAB_BAR_BOTTOM_OFFSET, TAB_BAR_HEIGHT } from '@/constants/TabBar';
+import { useColorScheme } from '@/hooks/useColorScheme';
 
 export default function TabLayout() {
+  const theme = (useColorScheme() ?? 'light') as 'light' | 'dark';
+  const colorTokens = Colors[theme];
   const pathname = usePathname();
 
   return (
@@ -19,9 +23,9 @@ export default function TabLayout() {
 
         return {
           headerShown: false,
-          tabBarActiveTintColor: '#192126',
+          tabBarActiveTintColor: colorTokens.tabIconSelected,
           tabBarButton: (props) => {
-            const { children, onPress } = props;
+            const { onPress } = props;
 
             const handlePress = (event: any) => {
               if (process.env.EXPO_OS === 'ios') {
@@ -30,9 +34,28 @@ export default function TabLayout() {
               onPress && onPress(event);
             };
 
+            // 基于 routeName 设置图标与标题，避免 tabBarIcon 的包装导致文字裁剪
+            const getIconAndTitle = () => {
+              switch (routeName) {
+                case 'index':
+                  return { icon: 'house.fill', title: '首页' } as const;
+                case 'explore':
+                  return { icon: 'paperplane.fill', title: '探索' } as const;
+                case 'personal':
+                  return { icon: 'person.fill', title: '个人' } as const;
+                default:
+                  return { icon: 'circle', title: '' } as const;
+              }
+            };
+
+            const { icon, title } = getIconAndTitle();
+            const activeContentColor = colorTokens.onPrimary;
+            const inactiveContentColor = colorTokens.tabIconDefault;
+
             return (
               <TouchableOpacity
                 onPress={handlePress}
+                accessibilityRole="button"
                 style={{
                   flex: 1,
                   alignItems: 'center',
@@ -41,12 +64,32 @@ export default function TabLayout() {
                   marginHorizontal: 6,
                   marginVertical: 10,
                   borderRadius: 25,
-                  backgroundColor: isSelected ? '#BBF246' : 'transparent',
-                  paddingHorizontal: isSelected ? 16 : 8,
+                  backgroundColor: isSelected ? colorTokens.tabBarActiveBackground : 'transparent',
+                  paddingHorizontal: isSelected ? 16 : 10,
                   paddingVertical: 8,
                 }}
               >
-                {children}
+                <View style={{ flexDirection: 'row', alignItems: 'center' }}>
+                  <IconSymbol
+                    size={22}
+                    name={icon as any}
+                    color={isSelected ? activeContentColor : inactiveContentColor}
+                  />
+                  {isSelected && !!title && (
+                    <Text
+                      style={{
+                        color: activeContentColor,
+                        fontSize: 12,
+                        fontWeight: '600',
+                        marginLeft: 6,
+                      }}
+                      // 选中态下不限制行数，避免大屏布局下被裁剪成省略号
+                      numberOfLines={0 as any}
+                    >
+                      {title}
+                    </Text>
+                  )}
+                </View>
               </TouchableOpacity>
             );
           },
@@ -55,7 +98,7 @@ export default function TabLayout() {
             bottom: TAB_BAR_BOTTOM_OFFSET,
             height: TAB_BAR_HEIGHT,
             borderRadius: 34,
-            backgroundColor: '#192126',
+            backgroundColor: colorTokens.tabBarBackground,
             shadowColor: '#000',
             shadowOffset: { width: 0, height: 2 },
             shadowOpacity: 0.2,