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.Client/Components/Admin/Pages/Blog/BlogCreate.razor

@@ -0,0 +1,65 @@
+@page "/admin/blog/create"
+@attribute [Authorize]
+@using TaxBaik.Application.DTOs
+@using TaxBaik.WasmClient.Components.Admin.Pages.Blog
+@inject IBlogBrowserClient BlogClient
+@inject ICategoryBrowserClient CategoryClient
+@inject NavigationManager Navigation
+@inject ISnackbar Snackbar
+
+<PageTitle>새 포스트 작성</PageTitle>
+
+<AdminCrudPageShell Title="새 포스트 작성"
+                    Eyebrow="Content"
+                    Subtitle="새로운 블로그 포스트를 작성합니다."
+                    Loading="@false"
+                    OnCancel="@GoBack">
+    <MudPaper Class="pa-4 mt-4" Elevation="1">
+        <BlogForm Model="model" Categories="categories" SubmitText="저장" OnSubmit="SavePost" OnCancel="GoBack" />
+    </MudPaper>
+</AdminCrudPageShell>
+
+@code {
+    private IReadOnlyList<Domain.Entities.Category> categories = [];
+    private BlogForm.BlogFormModel model = new();
+
+    protected override async Task OnInitializedAsync()
+    {
+        categories = await CategoryClient.GetAllAsync();
+    }
+
+    private void GoBack()
+    {
+        Navigation.NavigateTo("/taxbaik/admin/blog");
+    }
+
+    private async Task SavePost()
+    {
+        try
+        {
+            var result = await BlogClient.CreateAsync(new CreateBlogPostDto
+            {
+                Title = model.Title,
+                Content = model.Content,
+                CategoryId = model.CategoryId,
+                Tags = model.Tags,
+                SeoTitle = model.SeoTitle,
+                SeoDescription = model.SeoDescription,
+                IsPublished = model.IsPublished
+            });
+
+            if (result == null)
+            {
+                Snackbar.Add("포스트 저장에 실패했습니다.", Severity.Error);
+                return;
+            }
+
+            Snackbar.Add("포스트가 저장되었습니다.", Severity.Success);
+            Navigation.NavigateTo("/taxbaik/admin/blog");
+        }
+        catch (ValidationException ex)
+        {
+            Snackbar.Add(ex.Message, Severity.Error);
+        }
+    }
+}