refactor: complete WebAssembly migration - proper architecture

Phase 8: Complete WebAssembly 렌더 모드 전환 (정공법)

Migration Summary:
- ALL Admin components → TaxBaik.Web.Client
- Routes.razor, Pages/*, Layout/*, Shared/*, Forms/*
- App.razor → TaxBaik.WasmClient (호스트 컴포넌트)
- Shared utilities → TaxBaik.Application.Utils

Architecture:
✅ App.razor: TaxBaik.WasmClient (WebAssembly, 호스트)
✅ Routes + Pages: TaxBaik.WasmClient (WebAssembly)
✅ Layout + Shared + Forms: TaxBaik.WasmClient (WebAssembly)
✅ Services: TaxBaik.Web (API-First)

Key Changes:
- Namespaces: TaxBaik.Web.Components.Admin → TaxBaik.WasmClient.Components.Admin
- Shared utilities: TaxBaik.Application.Utils (single source of truth)
- Program.cs: MapRazorComponents<TaxBaik.WasmClient.Components.Admin.App>()
- _Imports.razor: Components/Admin 폴더에 재구성

Build Status: ✅ 0 errors, 0 warnings

Benefits:
- Stateless server (no Circuit memory)
- Client-side rendering (WebAssembly)
- Unlimited concurrent users (horizontal scaling)
- ERP-ready architecture

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

TaxBaik.Web/Components/Admin/Routes.razor

@@ -1,19 +0,0 @@
-@namespace TaxBaik.Web.Components.Admin
-@using Microsoft.AspNetCore.Components.Routing
-
-<Router AppAssembly="@typeof(Program).Assembly">
-    <Found Context="routeData">
-        <AuthorizeRouteView RouteData="@routeData" DefaultLayout="@typeof(TaxBaik.Web.Components.Admin.Layout.MainLayout)">
-            <NotAuthorized>
-                <RedirectToLogin />
-            </NotAuthorized>
-        </AuthorizeRouteView>
-        <FocusOnNavigate RouteData="@routeData" Selector="h1" />
-    </Found>
-    <NotFound>
-        <PageTitle>찾을 수 없음</PageTitle>
-        <LayoutView Layout="@typeof(TaxBaik.Web.Components.Admin.Layout.MainLayout)">
-            <p>요청한 페이지를 찾을 수 없습니다.</p>
-        </LayoutView>
-    </NotFound>
-</Router>