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/Program.cs

@@ -76,6 +76,16 @@ builder.Services.AddHttpClient<IAdminDashboardClient, AdminDashboardClient>(clie
 })
     .AddHttpMessageHandler<TokenRefreshHandler>();
 builder.Services.AddHttpClient<IInquiryBrowserClient, InquiryBrowserClient>(client =>
+{
+    client.BaseAddress = new Uri("http://localhost:5001/taxbaik/api/");
+})
+    .AddHttpMessageHandler<TokenRefreshHandler>();
+builder.Services.AddHttpClient<IClientBrowserClient, ClientBrowserClient>(client =>
+{
+    client.BaseAddress = new Uri("http://localhost:5001/taxbaik/api/");
+})
+    .AddHttpMessageHandler<TokenRefreshHandler>();
+builder.Services.AddHttpClient<ITaxFilingBrowserClient, TaxFilingBrowserClient>(client =>
 {
     client.BaseAddress = new Uri("http://localhost:5001/taxbaik/api/");
 })