Add JWT authentication and authorization infrastructure

Distribution/Features/Auth/AuthService.cs

@@ -0,0 +1,24 @@
+using Distribution.Features.User;
+using Distribution.Infra.Auth;
+using Microsoft.AspNetCore.Identity;
+
+namespace Distribution.Features.Auth;
+
+public class AuthService(IUserRepository userRepo, IJwtTokenService tokenService)
+{
+    private readonly PasswordHasher<Models.User> _hasher = new();
+
+    public async Task<LoginResponse?> LoginAsync(LoginRequest request)
+    {
+        var user = await userRepo.GetByUsernameAsync(request.Username);
+        if (user is null || !user.IsActive)
+            return null;
+
+        var result = _hasher.VerifyHashedPassword(user, user.PasswordHash, request.Password);
+        if (result == PasswordVerificationResult.Failed)
+            return null;
+
+        var token = tokenService.GenerateToken(user);
+        return new LoginResponse(token, user.Id, user.Username, user.Role?.Name ?? string.Empty);
+    }
+}