feat: implement TaxProfiles Blazor page with MudDataGrid

Step 3 Progress:
- Create TaxProfiles.razor list page with MudDataGrid (Dense, Virtualize)
- Implement ConfirmDialog component for delete confirmation
- Add MudDialog create/edit modal (no white-screen flash)
- Use ITaxProfileBrowserClient for API calls
- Map ClientBrowserClient.GetPagedAsync() for client dropdown

Browser Client Fixes:
- Fix CreateAsync JsonElement deserialization in 4 files (ContractBrowserClient, ConsultingActivityBrowserClient, TaxFilingScheduleBrowserClient, RevenueTrackingBrowserClient)
- Fix ITaxProfileBrowserClient CreateAsync (JsonElement pattern)
- Remove duplicate IClientBrowserClient from AdminClients namespace

Architectural Decisions:
- Reuse existing ClientBrowserClient.GetPagedAsync() (Paged, Search, Filter support)
- MudDialog for create/edit (prevents white-screen navigation flashes)
- Inline actions (Edit/Delete buttons) vs separate routes
- ConfirmDialog for destructive operations

UI Patterns:
- Dense grid (32px rows), 30 rows per page
- Status color chips (Error/Warning/Success for risk levels)
- Client link to /admin/clients/{id}
- Client dropdown from API (paged response)

Build Status: 0 errors (3 existing warnings)

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

TaxBaik.Web/Services/AdminClients/ITaxProfileBrowserClient.cs

@@ -100,8 +100,8 @@ public class TaxProfileBrowserClient(HttpClient httpClient, ILogger<TaxProfileBr
             var request = new { clientId, businessType, businessRegistration, accountingMethod, establishmentDate };
             var response = await httpClient.PostAsJsonAsync(BaseUrl, request, ct);
             response.EnsureSuccessStatusCode();
-            var result = await response.Content.ReadFromJsonAsync<dynamic>(cancellationToken: ct);
-            return result?["id"]?.ToObject<int>() ?? 0;
+            var result = await response.Content.ReadFromJsonAsync<JsonElement>(cancellationToken: ct);
+            return result.TryGetProperty("id", out var idProp) ? idProp.GetInt32() : 0;
         }
         catch (Exception ex)
         {