feat: 添加用户登录和法律协议页面

- 新增登录页面，支持 Apple 登录和游客登录功能
- 添加用户协议和隐私政策页面，用户需同意后才能登录
- 更新首页逻辑，首次进入时自动跳转到登录页面
- 修改个人信息页面，移除单位选择功能，统一使用 kg 和 cm
- 更新依赖，添加 expo-apple-authentication 库以支持 Apple 登录
- 更新布局以适应新功能的展示和交互

app/profile/edit.tsx

@@ -4,7 +4,7 @@ import { Ionicons } from '@expo/vector-icons';
 import AsyncStorage from '@react-native-async-storage/async-storage';
 import * as ImagePicker from 'expo-image-picker';
 import { router } from 'expo-router';
-import React, { useEffect, useMemo, useState } from 'react';
+import React, { useEffect, useState } from 'react';
 import {
   Alert,
   Image,
@@ -32,10 +32,6 @@ interface UserProfile {
   weightKg?: number; // kg
   heightCm?: number; // cm
   avatarUri?: string | null;
-  unitPref?: {
-    weight: WeightUnit;
-    height: HeightUnit;
-  };
 }
 
 const STORAGE_KEY = '@user_profile';
@@ -52,26 +48,12 @@ export default function EditProfileScreen() {
     weightKg: undefined,
     heightCm: undefined,
     avatarUri: null,
-    unitPref: { weight: 'kg', height: 'cm' },
   });
 
   const [weightInput, setWeightInput] = useState<string>('');
   const [heightInput, setHeightInput] = useState<string>('');
 
-  // 将存储的公制值转换为当前选择单位显示
-  const displayedWeight = useMemo(() => {
-    if (profile.weightKg == null || isNaN(profile.weightKg)) return '';
-    return profile.unitPref?.weight === 'kg'
-      ? String(round(profile.weightKg, 1))
-      : String(round(kgToLb(profile.weightKg), 1));
-  }, [profile.weightKg, profile.unitPref?.weight]);
-
-  const displayedHeight = useMemo(() => {
-    if (profile.heightCm == null || isNaN(profile.heightCm)) return '';
-    return profile.unitPref?.height === 'cm'
-      ? String(Math.round(profile.heightCm))
-      : String(round(cmToFt(profile.heightCm), 1));
-  }, [profile.heightCm, profile.unitPref?.height]);
+  // 输入框字符串
 
   useEffect(() => {
     (async () => {
@@ -89,7 +71,6 @@ export default function EditProfileScreen() {
           weightKg: undefined,
           heightCm: undefined,
           avatarUri: null,
-          unitPref: { weight: 'kg', height: 'cm' },
         };
 
         if (fromOnboarding) {
@@ -109,8 +90,8 @@ export default function EditProfileScreen() {
           } catch { }
         }
         setProfile(next);
-        setWeightInput(next.weightKg != null ? (next.unitPref?.weight === 'kg' ? String(round(next.weightKg, 1)) : String(round(kgToLb(next.weightKg), 1))) : '');
-        setHeightInput(next.heightCm != null ? (next.unitPref?.height === 'cm' ? String(Math.round(next.heightCm)) : String(round(cmToFt(next.heightCm), 1))) : '');
+        setWeightInput(next.weightKg != null ? String(round(next.weightKg, 1)) : '');
+        setHeightInput(next.heightCm != null ? String(Math.round(next.heightCm)) : '');
       } catch (e) {
         console.warn('读取资料失败', e);
       }
@@ -124,17 +105,17 @@ export default function EditProfileScreen() {
     try {
       const next: UserProfile = { ...profile };
 
-      // 将当前输入反向同步为公制
+      // 将当前输入同步为公制（固定 kg/cm）
       const w = parseFloat(weightInput);
       if (!isNaN(w)) {
-        next.weightKg = profile.unitPref?.weight === 'kg' ? w : lbToKg(w);
+        next.weightKg = w;
       } else {
         next.weightKg = undefined;
       }
 
       const h = parseFloat(heightInput);
       if (!isNaN(h)) {
-        next.heightCm = profile.unitPref?.height === 'cm' ? h : ftToCm(h);
+        next.heightCm = h;
       } else {
         next.heightCm = undefined;
       }
@@ -147,27 +128,7 @@ export default function EditProfileScreen() {
     }
   };
 
-  const toggleWeightUnit = (unit: WeightUnit) => {
-    if (unit === profile.unitPref?.weight) return;
-    const current = parseFloat(weightInput);
-    let nextValueStr = weightInput;
-    if (!isNaN(current)) {
-      nextValueStr = unit === 'kg' ? String(round(lbToKg(current), 1)) : String(round(kgToLb(current), 1));
-    }
-    setProfile((p) => ({ ...p, unitPref: { ...(p.unitPref || { weight: 'kg', height: 'cm' }), weight: unit } }));
-    setWeightInput(nextValueStr);
-  };
-
-  const toggleHeightUnit = (unit: HeightUnit) => {
-    if (unit === profile.unitPref?.height) return;
-    const current = parseFloat(heightInput);
-    let nextValueStr = heightInput;
-    if (!isNaN(current)) {
-      nextValueStr = unit === 'cm' ? String(Math.round(ftToCm(current))) : String(round(cmToFt(current), 1));
-    }
-    setProfile((p) => ({ ...p, unitPref: { ...(p.unitPref || { weight: 'kg', height: 'cm' }), height: unit } }));
-    setHeightInput(nextValueStr);
-  };
+  // 不再需要单位切换
 
   const pickAvatarFromLibrary = async () => {
     try {
@@ -235,44 +196,36 @@ export default function EditProfileScreen() {
             {!!profile.fullName && <Text style={{ color: '#C4C4C4' }}>✓</Text>}
           </View>
 
-          {/* 体重 */}
+          {/* 体重（kg） */}
           <FieldLabel text="体重" />
           <View style={styles.row}>
             <View style={[styles.inputWrapper, styles.flex1, { borderColor: '#E0E0E0' }]}>
               <TextInput
                 style={[styles.textInput, { color: textColor }]}
-                placeholder={profile.unitPref?.weight === 'kg' ? '输入体重' : '输入体重'}
+                placeholder={'输入体重'}
                 placeholderTextColor={placeholderColor}
                 keyboardType="numeric"
                 value={weightInput}
                 onChangeText={setWeightInput}
               />
+              <Text style={{ color: '#5E6468', marginLeft: 6 }}>kg</Text>
             </View>
-            <SegmentedTwo
-              options={[{ key: 'lb', label: 'LBS' }, { key: 'kg', label: 'KG' }]}
-              activeKey={profile.unitPref?.weight || 'kg'}
-              onChange={(key) => toggleWeightUnit(key as WeightUnit)}
-            />
           </View>
 
-          {/* 身高 */}
+          {/* 身高（cm） */}
           <FieldLabel text="身高" />
           <View style={styles.row}>
             <View style={[styles.inputWrapper, styles.flex1, { borderColor: '#E0E0E0' }]}>
               <TextInput
                 style={[styles.textInput, { color: textColor }]}
-                placeholder={profile.unitPref?.height === 'cm' ? '输入身高' : '输入身高'}
+                placeholder={'输入身高'}
                 placeholderTextColor={placeholderColor}
                 keyboardType="numeric"
                 value={heightInput}
                 onChangeText={setHeightInput}
               />
+              <Text style={{ color: '#5E6468', marginLeft: 6 }}>cm</Text>
             </View>
-            <SegmentedTwo
-              options={[{ key: 'ft', label: 'FEET' }, { key: 'cm', label: 'CM' }]}
-              activeKey={profile.unitPref?.height || 'cm'}
-              onChange={(key) => toggleHeightUnit(key as HeightUnit)}
-            />
           </View>
 
           {/* 性别 */}
@@ -323,29 +276,10 @@ function FieldLabel({ text }: { text: string }) {
   );
 }
 
-function SegmentedTwo(props: {
-  options: { key: string; label: string }[];
-  activeKey: string;
-  onChange: (key: string) => void;
-}) {
-  const { options, activeKey, onChange } = props;
-  return (
-    <View style={[styles.segmented, { backgroundColor: '#EFEFEF' }]}>
-      {options.map((opt) => (
-        <TouchableOpacity
-          key={opt.key}
-          style={[styles.segmentBtn, activeKey === opt.key && { backgroundColor: '#FFFFFF' }]}
-          onPress={() => onChange(opt.key)}
-          activeOpacity={0.8}
-        >
-          <Text style={{ fontSize: 14, fontWeight: '600', color: activeKey === opt.key ? '#000' : '#5E6468' }}>{opt.label}</Text>
-        </TouchableOpacity>
-      ))}
-    </View>
-  );
-}
+// 单位切换组件已移除（固定 kg/cm）
 
 // 工具函数
+// 转换函数不再使用，保留 round
 function kgToLb(kg: number) { return kg * 2.2046226218; }
 function lbToKg(lb: number) { return lb / 2.2046226218; }
 function cmToFt(cm: number) { return cm / 30.48; }