feat(portal): 고객 포털 인증과 소셜 로그인 기반 추가

TaxBaik.Domain/Entities/PortalUser.cs

@@ -0,0 +1,14 @@
+namespace TaxBaik.Domain.Entities;
+
+public class PortalUser
+{
+    public int Id { get; set; }
+    public int? ClientId { get; set; }
+    public string Email { get; set; } = "";
+    public string Name { get; set; } = "";
+    public string? Phone { get; set; }
+    public string Provider { get; set; } = "local";
+    public string? ProviderId { get; set; }
+    public string? PasswordHash { get; set; }
+    public DateTime CreatedAt { get; set; }
+}

TaxBaik.Domain/Interfaces/IPortalUserRepository.cs

@@ -0,0 +1,12 @@
+namespace TaxBaik.Domain.Interfaces;
+
+using TaxBaik.Domain.Entities;
+
+public interface IPortalUserRepository
+{
+    Task<PortalUser?> GetByIdAsync(int id, CancellationToken ct = default);
+    Task<PortalUser?> GetByEmailAsync(string email, CancellationToken ct = default);
+    Task<PortalUser?> GetByProviderAsync(string provider, string providerId, CancellationToken ct = default);
+    Task<int> CreateAsync(PortalUser user, CancellationToken ct = default);
+    Task UpdateAsync(PortalUser user, CancellationToken ct = default);
+}