refactor: fully integrate Browser Client into main Web server

BREAKING CHANGE: Removed TaxBaik.Web.Client project (separate WASM app)

Changes:
- Migrated all Blazor components to TaxBaik.Web/Components/Admin
- Migrated all Browser Client services to Components/Admin/Services
- Updated Program.cs to use integrated components (same assembly)
- Removed AddAdditionalAssemblies (no longer needed)
- Updated _Imports.razor with correct namespaces

Architecture:
✅ API-First: REST endpoints in TaxBaik.Web (ASP.NET Core)
✅ Client-Side: Blazor WASM components in TaxBaik.Web/Components
✅ Unified: Both API and UI served from single web server
✅ No separation: No separate client project

Result:
- Single deploy unit (TaxBaik.Web)
- API served only from web server
- Blazor renders client-side (prerender: false for protected pages)
- Monolithic web app architecture

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

src/TaxBaik.Web/Program.cs

@@ -402,12 +402,11 @@ app.MapStaticAssets();
 // AllowAnonymous: JWT 미들웨어가 Blazor 셸 요청을 401로 차단하지 않도록 한다.
 // 인증은 Blazor AuthorizeRouteView → RedirectToLogin 에서 처리한다.
 // Phase 8: WebAssembly 렌더 모드 완전 마이그레이션
-// - App.razor: TaxBaik.WasmClient (호스트, WebAssembly)
-// - Routes + Pages + Shared + Layout + Forms: TaxBaik.WasmClient (WebAssembly)
-// MapRazorComponents는 자동으로 root 컴포넌트의 어셈블리 로드
-// 동일 어셈블리의 Page/Shared 컴포넌트는 자동 발견되므로 AddAdditionalAssemblies 불필요
-// (같은 어셈블리를 2번 등록하면 "Assembly already defined" 에러 발생)
-app.MapRazorComponents<TaxBaik.WasmClient.Components.Admin.App>()
+// - App.razor: TaxBaik.Web (메인 웹 서버)
+// - Routes + Pages + Shared + Layout + Forms: TaxBaik.Web (메인 웹 서버)
+// 모든 Blazor 컴포넌트가 웹 서버에서 통합 서비스됨
+// API는 웹 서버에서만 제공 (클라이언트 프로젝트 분리 불필요)
+app.MapRazorComponents<TaxBaik.Web.Components.Admin.App>()
    .AddInteractiveWebAssemblyRenderMode()
    .AllowAnonymous();