feat: 启用百度云 SMS 真实验证码发送

- SmsService: 从开发桩改为调用 BceSmsClient.SendAsync 真实发送
- AuthService.SendCodeAsync: 加 60 秒冷却 + 发送结果检查（失败返回 40010）
- Program.cs: 注册 BceSmsClient 到 DI（AddHttpClient + 10s 超时）
- auth_tests.cs: 加 CreateSmsService helper 适配构造注入

移动号实测可收到验证码，联通号运营商环节待报备

backend/tests/Health.Tests/auth_tests.cs

@@ -5,6 +5,7 @@ using Health.Infrastructure.Data;
 using Health.Infrastructure.Services;
 using Microsoft.EntityFrameworkCore;
 using Microsoft.Extensions.Configuration;
+using Microsoft.Extensions.Logging.Abstractions;
 
 namespace Health.Tests;
 
@@ -32,12 +33,16 @@ public class AuthTests
         return new ConfigurationBuilder().AddInMemoryCollection(settings).Build();
     }
 
+    private static SmsService CreateSmsService() =>
+        new(new BceSmsClient(new HttpClient(), new ConfigurationBuilder().Build(), NullLogger<BceSmsClient>.Instance),
+            NullLogger<SmsService>.Instance);
+
     [Fact]
     public async Task SendSms_Should_Create_VerificationCode()
     {
         // Arrange
         using var db = CreateDbContext();
-        var sms = new SmsService();
+        var sms = CreateSmsService();
 
         // Act
         var code = sms.GenerateCode();
@@ -148,7 +153,7 @@ public class AuthTests
         var service = new AuthService(
             db,
             jwt,
-            new SmsService(),
+            CreateSmsService(),
             new AppleTokenValidator(config));
 
         var result = await service.RefreshAsync(oldRefresh, CancellationToken.None);