Refactor admin login to cookie auth

src/TaxBaik.Web/Program.cs

@@ -115,7 +115,7 @@ builder.Services.AddSession(options =>
 builder.Services.AddDistributedMemoryCache();
 // TempData는 기본적으로 쿠키 저장소 사용 (위 세션 설정 상속)
 
-// JWT 인증
+// 인증: 관리자 쿠키 + 포털 쿠키 + 기존 JWT(과도기 API)
 var connectionString = builder.Configuration.GetConnectionString("Default")
     ?? throw new InvalidOperationException("Missing connection string");
 var jwtKey = builder.Configuration["Jwt:SecretKey"] ?? throw new InvalidOperationException("Missing JWT SecretKey");
@@ -153,6 +153,17 @@ var authenticationBuilder = builder.Services.AddAuthentication(opts =>
     opts.SlidingExpiration = true;
     opts.ExpireTimeSpan = TimeSpan.FromDays(7);
 })
+.AddCookie(AdminAuthDefaults.Scheme, opts =>
+{
+    opts.Cookie.Name = AdminAuthDefaults.CookieName;
+    opts.Cookie.HttpOnly = true;
+    opts.Cookie.SameSite = SameSiteMode.Lax;
+    opts.Cookie.SecurePolicy = isProduction ? CookieSecurePolicy.Always : CookieSecurePolicy.SameAsRequest;
+    opts.LoginPath = "/admin/login";
+    opts.AccessDeniedPath = "/admin/login";
+    opts.SlidingExpiration = true;
+    opts.ExpireTimeSpan = TimeSpan.FromHours(12);
+})
 .AddCookie(PortalOAuthDefaults.ExternalScheme, opts =>
 {
     opts.Cookie.Name = "TaxBaik.Portal.External";