수정: 빌드 오류 해결 (PageModel 네임스페이스, Blazor 문법, 응답 압축)

- @model 선언에 정확한 네임스페이스 지정
- Snackbar 호출 수정 (MudBlazor 6.x 호환)
- GzipCompressionProvider import 추가
- Dashboard Color.TextSecondary 제거
- Admin App.razor MUI CSS 제거

Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>

TaxBaik.Infrastructure/Repositories/BaseRepository.cs

@@ -5,5 +5,7 @@ using TaxBaik.Domain.Interfaces;
 
 public abstract class BaseRepository(IDbConnectionFactory connectionFactory)
 {
-    protected IDbConnection Conn() => connectionFactory.CreateConnection();
+    protected readonly IDbConnectionFactory _connectionFactory = connectionFactory;
+
+    protected IDbConnection Conn() => _connectionFactory.CreateConnection();
 }