fix(auth): Remove hardcoded api/v1 prefix from AuthController route

ApiPrefixConvention already prepends api/v1 to all controllers.
AuthController had it hardcoded too, resulting in the doubled route
api/v1/api/v1/auth/login which caused a 404 on login attempts.

Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>

src/SlpModularCms.Modules.Identity/Controllers/AuthController.cs

@@ -8,7 +8,7 @@ using SlpModularCms.Core.Identity.Services;
 namespace SlpModularCms.Modules.Identity.Controllers;
 
 [ApiController]
-[Route("api/v1/auth")]
+[Route("auth")]
 public class AuthController : ControllerBase
 {
     private readonly IAuthService _authService;