feat: 添加教练功能和更新用户界面

- 新增教练页面，用户可以与教练进行互动和咨询
- 更新首页，切换到教练 tab 并传递名称参数
- 优化个人信息页面，添加注销帐号和退出登录功能
- 更新隐私政策和用户协议的链接，确保用户在使用前同意相关条款
- 修改今日训练页面标题为“开始训练”，提升用户体验
- 删除不再使用的进度条组件，简化代码结构

app/auth/login.tsx

@@ -3,11 +3,12 @@ import * as AppleAuthentication from 'expo-apple-authentication';
 import { LinearGradient } from 'expo-linear-gradient';
 import { useLocalSearchParams, useRouter } from 'expo-router';
 import React, { useCallback, useEffect, useMemo, useRef, useState } from 'react';
-import { Alert, Animated, Pressable, ScrollView, StyleSheet, Text, TouchableOpacity, View } from 'react-native';
+import { Alert, Animated, Linking, Pressable, ScrollView, StyleSheet, Text, TouchableOpacity, View } from 'react-native';
 import { SafeAreaView } from 'react-native-safe-area-context';
 
 import { ThemedText } from '@/components/ThemedText';
 import { ThemedView } from '@/components/ThemedView';
+import { PRIVACY_POLICY_URL, USER_AGREEMENT_URL } from '@/constants/Agree';
 import { Colors } from '@/constants/Colors';
 import { useAppDispatch } from '@/hooks/redux';
 import { useColorScheme } from '@/hooks/useColorScheme';
@@ -230,8 +231,8 @@ export default function LoginScreen() {
 
         <ScrollView contentContainerStyle={styles.content} showsVerticalScrollIndicator={false}>
           <View style={styles.headerWrap}>
-            <ThemedText style={[styles.title, { color: color.text }]}>数字普拉提</ThemedText>
-            <ThemedText style={[styles.subtitle, { color: color.textMuted }]}>欢迎登录</ThemedText>
+            <ThemedText style={[styles.title, { color: color.text }]}>普拉提助手</ThemedText>
+            <ThemedText style={[styles.subtitle, { color: color.textMuted }]}>欢迎登录普拉提星球</ThemedText>
           </View>
 
           {/* Apple 登录 */}
@@ -252,22 +253,6 @@ export default function LoginScreen() {
             </Pressable>
           )}
 
-          {/* 游客登录（弱化样式） */}
-          <Pressable
-            accessibilityRole="button"
-            onPress={() => guardAgreement(onGuestLogin)}
-            disabled={loading}
-            style={({ pressed }) => [
-              styles.guestButton,
-              { borderColor: color.border, backgroundColor: color.surface },
-              loading && { opacity: 0.7 },
-              pressed && { transform: [{ scale: 0.98 }] },
-            ]}
-          >
-            <Ionicons name="person-circle-outline" size={22} color={color.neutral200} style={{ marginRight: 8 }} />
-            <Text style={[styles.guestText, { color: color.neutral200 }]}>以游客身份继续</Text>
-          </Pressable>
-
           {/* 协议勾选 */}
           <View style={styles.agreementRow}>
             <Pressable onPress={() => setHasAgreed((v) => !v)} style={styles.checkboxWrap} accessibilityRole="checkbox" accessibilityState={{ checked: hasAgreed }}>
@@ -281,11 +266,11 @@ export default function LoginScreen() {
               </View>
             </Pressable>
             <Text style={[styles.agreementText, { color: color.textMuted }]}>我已阅读并同意</Text>
-            <Pressable onPress={() => router.push('/legal/privacy-policy')}>
+            <Pressable onPress={() => Linking.openURL(PRIVACY_POLICY_URL)}>
               <Text style={[styles.link, { color: color.primary }]}>《隐私政策》</Text>
             </Pressable>
             <Text style={[styles.agreementText, { color: color.textMuted }]}>和</Text>
-            <Pressable onPress={() => router.push('/legal/user-agreement')}>
+            <Pressable onPress={() => Linking.openURL(USER_AGREEMENT_URL)}>
               <Text style={[styles.link, { color: color.primary }]}>《用户协议》</Text>
             </Pressable>
           </View>