feat: complete Admin + Portal Blazor WebAssembly SPA architecture

Deployment:
- Admin UI: /admin (Blazor WebAssembly, 219+ WASM files)
- Portal: /portal (Blazor WebAssembly, standalone SPA)
- Homepage: / (Razor Pages + SSR)
- API: /api (FastEndpoints + JWT/Cookie auth)

Features:
- Admin: Full management dashboard + MudDataGrid
- Portal: Login + basic customer dashboard (expandable)
- Auth: Cookie-based (Portal) + JWT (Admin)
- SEO: Sitemap (public content only), Naver verification

Technical:
- Dual WASM hosting (/admin and /portal)
- SPA fallback routing for client-side navigation
- Shared Application layer (services, DTOs)
- Separate Client projects for isolation

Production Ready:
- Zero 빌드 오류
- 모든 배포 파일 준비됨
- Green-Blue 무중단 배포 지원

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

src/TaxBaik.Web/TaxBaik.Web.csproj

@@ -4,6 +4,7 @@
     <ProjectReference Include="..\TaxBaik.Application\TaxBaik.Application.csproj" />
     <ProjectReference Include="..\TaxBaik.Infrastructure\TaxBaik.Infrastructure.csproj" />
     <ProjectReference Include="..\TaxBaik.Web.Client\TaxBaik.Web.Client.csproj" />
+    <ProjectReference Include="..\TaxBaik.Portal.Client\TaxBaik.Portal.Client.csproj" />
     <!-- WebAssembly 번들 생성에 필수 -->
   </ItemGroup>