fix: HttpClientFactory 생명주기 불일치(Scope Capture) 문제를 회피하기 위해 CRM API 클라이언트에 직접 토큰 주입하도록 전면 개편

TaxBaik.Web/Services/AdminDashboardClient.cs

@@ -33,10 +33,10 @@ public class AdminDashboardClient : IAdminDashboardClient
 
     private void EnsureAuthHeader()
     {
-        if (!string.IsNullOrEmpty(_tokenStore.AccessToken) && !_http.DefaultRequestHeaders.Contains("Authorization"))
-        {
+        if (!string.IsNullOrEmpty(_tokenStore.AccessToken))
             _http.DefaultRequestHeaders.Authorization = new("Bearer", _tokenStore.AccessToken);
-        }
+        else
+            _http.DefaultRequestHeaders.Authorization = null;
     }
 
     public async Task<AdminDashboardSummary> GetSummaryAsync(CancellationToken ct = default)