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.WebApi/Endpoints/auth_endpoints.cs

@@ -12,6 +12,8 @@ public static class AuthEndpoints
             ToResult(await auth.RegisterAsync(new RegisterCommand(request.Phone, request.SmsCode, request.Name, request.DoctorId), ct)));
         app.MapPost("/api/auth/login", async (LoginRequest request, IAuthService auth, CancellationToken ct) =>
             ToResult(await auth.LoginAsync(request.Phone, request.SmsCode, ct)));
+        app.MapPost("/api/auth/apple-login", async (AppleLoginRequest request, IAuthService auth, CancellationToken ct) =>
+            ToResult(await auth.AppleLoginAsync(new AppleLoginCommand(request.IdentityToken, request.AuthorizationCode, request.Name), ct)));
         app.MapPost("/api/auth/refresh", async (RefreshRequest request, IAuthService auth, CancellationToken ct) =>
             ToResult(await auth.RefreshAsync(request.RefreshToken, ct)));
         app.MapPost("/api/auth/logout", async (RefreshRequest request, IAuthService auth, CancellationToken ct) =>
@@ -28,4 +30,5 @@ public static class AuthEndpoints
 public sealed record SendSmsRequest(string Phone);
 public sealed record RegisterRequest(string Phone, string SmsCode, string Name, Guid DoctorId);
 public sealed record LoginRequest(string Phone, string SmsCode);
+public sealed record AppleLoginRequest(string IdentityToken, string? AuthorizationCode, string? Name);
 public sealed record RefreshRequest(string RefreshToken);