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/Components/Admin/Forms/CompanyForm.razor

@@ -0,0 +1,88 @@
+@using TaxBaik.Application.Services
+
+<MudForm @ref="form">
+    <MudTextField @bind-Value="model.CompanyCode" Label="회사 코드"
+        Variant="Variant.Outlined" Class="mb-4" Required="true"
+        HelperText="영문/숫자, 최대 50자" />
+
+    <MudTextField @bind-Value="model.CompanyName" Label="회사명"
+        Variant="Variant.Outlined" Class="mb-4" Required="true" />
+
+    <MudTextField @bind-Value="model.ContactPerson" Label="담당자명"
+        Variant="Variant.Outlined" Class="mb-4" />
+
+    <MudTextField @bind-Value="model.Phone" Label="전화번호"
+        Variant="Variant.Outlined" Class="mb-4" />
+
+    <MudTextField @bind-Value="model.Email" Label="이메일"
+        Variant="Variant.Outlined" Class="mb-4" InputType="InputType.Email" />
+
+    <MudTextField @bind-Value="model.Memo" Label="메모"
+        Variant="Variant.Outlined" Lines="3" Class="mb-4" />
+
+    <MudCheckBox @bind-Checked="model.IsActive" Label="활성" Class="mb-4" />
+
+    <div class="d-flex gap-2">
+        <MudButton Variant="Variant.Filled" Color="Color.Primary" @onclick="HandleSubmit">
+            @ButtonText
+        </MudButton>
+        <MudButton Variant="Variant.Outlined" @onclick="OnCancel">취소</MudButton>
+    </div>
+</MudForm>
+
+@code {
+    [Parameter, EditorRequired]
+    public string ButtonText { get; set; } = "저장";
+
+    [Parameter]
+    public EventCallback<CompanyFormModel> OnSubmit { get; set; }
+
+    [Parameter]
+    public EventCallback OnCancel { get; set; }
+
+    [Parameter]
+    public CompanyFormModel? InitialData { get; set; }
+
+    private MudForm? form;
+    private CompanyFormModel model = new();
+
+    protected override void OnInitialized()
+    {
+        if (InitialData != null)
+        {
+            model = new CompanyFormModel
+            {
+                CompanyCode = InitialData.CompanyCode,
+                CompanyName = InitialData.CompanyName,
+                ContactPerson = InitialData.ContactPerson,
+                Phone = InitialData.Phone,
+                Email = InitialData.Email,
+                Memo = InitialData.Memo,
+                IsActive = InitialData.IsActive
+            };
+        }
+    }
+
+    private async Task HandleSubmit()
+    {
+        if (form == null)
+            return;
+
+        await form.Validate();
+        if (!form.IsValid)
+            return;
+
+        await OnSubmit.InvokeAsync(model);
+    }
+
+    public class CompanyFormModel
+    {
+        public string CompanyCode { get; set; } = "";
+        public string CompanyName { get; set; } = "";
+        public string? ContactPerson { get; set; }
+        public string? Phone { get; set; }
+        public string? Email { get; set; }
+        public string? Memo { get; set; }
+        public bool IsActive { get; set; } = true;
+    }
+}