refactor: Phase 7-3 - Clients + TaxFilings API-First (WIP)

**Clients Migration Complete:**
- ClientController: GET /api/client (paged), POST/PUT/DELETE
- ClientBrowserClient: IClientBrowserClient interface + implementation
- ClientList.razor: Service → API client
- ClientEdit.razor: Service → API client (Create/Update)

**TaxFilings API Framework Ready:**
- TaxFilingController: GET upcoming, GET by client, POST/PUT/DELETE
- TaxFilingBrowserClient: ITaxFilingBrowserClient interface + impl
- Registered in Program.cs with TokenRefreshHandler

**SOLID Applied:**
✓ Separation of concerns (Controller → Service → Repository)
✓ Dependency inversion (Blazor → Browser clients, not services)
✓ Interface segregation (Specialized clients per domain)

**Status:**
- Clients Blazor: ✅ ClientList + ClientEdit refactored
- TaxFilings Blazor: ⏳ Pending refactor (pages exist)
- Faqs: ⏳ API + Blazor pending
- Announcements: ⏳ API + Blazor pending
- Phase 6 SignalR: ⏳ Deferred

Next: Refactor TaxFilings Blazor pages, then Faqs & Announcements
Build: ✅ Success (0 errors, 2 warnings in Dashboard)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

TaxBaik.Web/Components/Admin/Pages/Clients/ClientList.razor

@@ -1,8 +1,8 @@
 @page "/admin/clients"
 @attribute [Authorize]
-@using TaxBaik.Application.Services
+@using TaxBaik.Web.Services
 @using TaxBaik.Domain.Entities
-@inject ClientService ClientService
+@inject IClientBrowserClient ClientClient
 @inject NavigationManager Navigation
 @inject IDialogService DialogService
 @inject ISnackbar Snackbar
@@ -141,14 +141,24 @@
 
     private async Task LoadAsync()
     {
-        var (items, total) = await ClientService.GetPagedAsync(
-            currentPage, PageSize,
-            string.IsNullOrEmpty(statusFilter) ? null : statusFilter,
-            string.IsNullOrEmpty(searchText) ? null : searchText);
+        try
+        {
+            var (items, total) = await ClientClient.GetPagedAsync(
+                currentPage, PageSize,
+                string.IsNullOrEmpty(statusFilter) ? null : statusFilter,
+                string.IsNullOrEmpty(searchText) ? null : searchText);
 
-        clients = items.ToList();
-        totalCount = total;
-        totalPages = (int)Math.Ceiling((double)total / PageSize);
+            clients = items.ToList();
+            totalCount = total;
+            totalPages = (int)Math.Ceiling((double)total / PageSize);
+        }
+        catch (Exception ex)
+        {
+            Snackbar.Add($"오류: {ex.Message}", Severity.Error);
+            clients = [];
+            totalCount = 0;
+            totalPages = 0;
+        }
     }
 
     private async Task SearchAsync()
@@ -185,8 +195,23 @@
 
         if (confirmed != true) return;
 
-        await ClientService.DeleteAsync(client.Id);
-        Snackbar.Add($"{client.Name} 고객이 삭제되었습니다.", Severity.Success);
+        try
+        {
+            var success = await ClientClient.DeleteAsync(client.Id);
+            if (success)
+            {
+                Snackbar.Add($"{client.Name} 고객이 삭제되었습니다.", Severity.Success);
+                await LoadAsync();
+            }
+            else
+            {
+                Snackbar.Add("삭제에 실패했습니다.", Severity.Error);
+            }
+        }
+        catch (Exception ex)
+        {
+            Snackbar.Add($"오류: {ex.Message}", Severity.Error);
+        }
         await LoadAsync();
     }
 }