fix: update Service namespaces to match FastEndpoints structure

Fixed namespace mismatch:
- TaxBaik.Web.Services → TaxBaik.Web.Components.Admin.Services
- Browser Client services now properly discoverable
- _Imports.razor @using directives now resolve correctly

Build status: ✅ 0 errors, 68 warnings

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

src/TaxBaik.Web/Components/Admin/Services/FaqBrowserClient.cs

@@ -1,4 +1,4 @@
-namespace TaxBaik.Web.Services;
+namespace TaxBaik.Web.Components.Admin.Services;
 
 using System.Net.Http;
 using System.Net.Http.Json;