feat: 集成 Apple Sign-In + iOS 上线准备

- 后端新增 Apple 登录端点 /api/auth/apple-login
- 新增 AppleTokenValidator 验证 IdentityToken
- User 实体添加 AppleUserId 字段，Phone 改为可空
- 前端添加 sign_in_with_apple 依赖和 Apple 登录按钮
- 统一 Bundle ID 为 com.datalumina.YYA，显示名称为小脉健康
- 配置 DEVELOPMENT_TEAM 和 Sign in with Apple Entitlements
- 补充 NSCamera/NSPhotoLibrary 权限描述
- 生产 API 地址改为 https://erpapi.datalumina.cn/xiaomai
- Flutter 升级至 3.44.6 / Dart 3.12.2

Co-Authored-By: Claude <noreply@anthropic.com>

backend/src/Health.Application/Auth/AuthContracts.cs

@@ -2,12 +2,14 @@ namespace Health.Application.Auth;
 
 public sealed record AuthResult(int Code, object? Data, string? Message = null);
 public sealed record RegisterCommand(string Phone, string SmsCode, string Name, Guid DoctorId);
+public sealed record AppleLoginCommand(string IdentityToken, string? AuthorizationCode, string? Name);
 
 public interface IAuthService
 {
     Task<AuthResult> SendCodeAsync(string phone, bool revealDevelopmentCode, CancellationToken ct);
     Task<AuthResult> RegisterAsync(RegisterCommand command, CancellationToken ct);
     Task<AuthResult> LoginAsync(string phone, string smsCode, CancellationToken ct);
+    Task<AuthResult> AppleLoginAsync(AppleLoginCommand command, CancellationToken ct);
     Task<AuthResult> RefreshAsync(string refreshToken, CancellationToken ct);
     Task LogoutAsync(string refreshToken, CancellationToken ct);
 }

backend/src/Health.Application/Users/UserContracts.cs

@@ -4,7 +4,7 @@ namespace Health.Application.Users;
 
 public sealed record UserProfileDto(
     Guid Id,
-    string Phone,
+    string? Phone,  // Apple 用户无手机号
     string Role,
     string? Name,
     string? Gender,