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

ios/Podfile.lock

@@ -33,6 +33,8 @@ PODS:
     - ReactCommon/turbomodule/bridging
     - ReactCommon/turbomodule/core
     - Yoga
+  - ExpoAppleAuthentication (6.4.2):
+    - ExpoModulesCore
   - ExpoAsset (11.1.7):
     - ExpoModulesCore
   - ExpoBlur (14.1.5):
@@ -2156,6 +2158,7 @@ DEPENDENCIES:
   - EXConstants (from `../node_modules/expo-constants/ios`)
   - EXImageLoader (from `../node_modules/expo-image-loader/ios`)
   - Expo (from `../node_modules/expo`)
+  - ExpoAppleAuthentication (from `../node_modules/expo-apple-authentication/ios`)
   - ExpoAsset (from `../node_modules/expo-asset/ios`)
   - ExpoBlur (from `../node_modules/expo-blur/ios`)
   - ExpoFileSystem (from `../node_modules/expo-file-system/ios`)
@@ -2273,6 +2276,8 @@ EXTERNAL SOURCES:
     :path: "../node_modules/expo-image-loader/ios"
   Expo:
     :path: "../node_modules/expo"
+  ExpoAppleAuthentication:
+    :path: "../node_modules/expo-apple-authentication/ios"
   ExpoAsset:
     :path: "../node_modules/expo-asset/ios"
   ExpoBlur:
@@ -2465,6 +2470,7 @@ SPEC CHECKSUMS:
   EXConstants: 98bcf0f22b820f9b28f9fee55ff2daededadd2f8
   EXImageLoader: 4d3d3284141f1a45006cc4d0844061c182daf7ee
   Expo: a40d525c930dd1c8a158e082756ee071955baccb
+  ExpoAppleAuthentication: 8a661b6f4936affafd830f983ac22463c936dad5
   ExpoAsset: ef06e880126c375f580d4923fdd1cdf4ee6ee7d6
   ExpoBlur: 3c8885b9bf9eef4309041ec87adec48b5f1986a9
   ExpoFileSystem: 7f92f7be2f5c5ed40a7c9efc8fa30821181d9d63