feat(udt-001): api layer with AuthController, Program.cs and Serilog

src/api/SIGCM2.Api/Controllers/AuthController.cs

@@ -0,0 +1,48 @@
+using FluentValidation;
+using Microsoft.AspNetCore.Mvc;
+using SIGCM2.Application.Abstractions;
+using SIGCM2.Application.Auth.Login;
+
+namespace SIGCM2.Api.Controllers;
+
+[ApiController]
+[Route("api/v1/auth")]
+public sealed class AuthController : ControllerBase
+{
+    private readonly IDispatcher _dispatcher;
+    private readonly IValidator<LoginCommand> _validator;
+
+    public AuthController(IDispatcher dispatcher, IValidator<LoginCommand> validator)
+    {
+        _dispatcher = dispatcher;
+        _validator = validator;
+    }
+
+    /// <summary>Authenticates a user and returns a JWT access token.</summary>
+    /// <response code="200">Returns access token and refresh token.</response>
+    /// <response code="400">Validation error — missing or empty fields.</response>
+    /// <response code="401">Invalid credentials.</response>
+    [HttpPost("login")]
+    [ProducesResponseType(typeof(LoginResponseDto), StatusCodes.Status200OK)]
+    [ProducesResponseType(StatusCodes.Status400BadRequest)]
+    [ProducesResponseType(StatusCodes.Status401Unauthorized)]
+    public async Task<IActionResult> Login([FromBody] LoginRequest request)
+    {
+        var command = new LoginCommand(request.Username ?? string.Empty, request.Password ?? string.Empty);
+
+        var validation = await _validator.ValidateAsync(command);
+        if (!validation.IsValid)
+        {
+            var errors = validation.Errors
+                .GroupBy(e => e.PropertyName)
+                .ToDictionary(g => g.Key, g => g.Select(e => e.ErrorMessage).ToArray());
+            return BadRequest(new { errors });
+        }
+
+        var result = await _dispatcher.Send<LoginCommand, LoginResponseDto>(command);
+        return Ok(result);
+    }
+}
+
+/// <summary>Login request body — nullable to catch missing field scenarios.</summary>
+public sealed record LoginRequest(string? Username, string? Password);