ux: eliminate white-flash on Blazor navigation from Inquiry page

- App.razor: loading overlay starts with `show` class (visible on cold load)
- admin-session.js: add showLoading()/hideLoading(); MutationObserver detects
  .admin-page-hero / .admin-login-page instead of mud-element count threshold;
  observer restarts on every navigation cycle via LocationChanged
- MainLayout.razor: subscribe to NavigationManager.LocationChanged →
  call JS showLoading() on every route change; implements IDisposable
- InquiryList.razor: remove unused IInquiryRepository injection; load data
  once (GetPagedAsync(1,200)) and pass IReadOnlyList to all six tab panels
- InquiryTable.razor: accept Inquiries parameter; filter synchronously in
  OnParametersSet() — eliminates 6 redundant API calls per page visit
- admin.css: overlay fade-in animation (0.15s); page content fade-in on
  route mount via .admin-page-hero / .admin-login-page animation (0.25s)

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

TaxBaik.Web/Components/Admin/InquiryTable.razor

@@ -1,6 +1,3 @@
-@using TaxBaik.Web.Services
-@inject IInquiryBrowserClient InquiryClient
-
 <MudSimpleTable Striped="true" Dense="true" Class="admin-table mt-4">
     <thead>
         <tr>
@@ -37,24 +34,19 @@
 </MudSimpleTable>
 
 @code {
+    [Parameter, EditorRequired]
+    public IReadOnlyList<Domain.Entities.Inquiry> Inquiries { get; set; } = [];
+
     [Parameter]
     public string Status { get; set; } = "";
 
-    private List<Domain.Entities.Inquiry> inquiries = [];
-    private List<Domain.Entities.Inquiry> filteredInquiries = [];
+    private IReadOnlyList<Domain.Entities.Inquiry> filteredInquiries = [];
 
-    protected override async Task OnInitializedAsync()
-    {
-        var (items, _) = await InquiryClient.GetPagedAsync(1, 100);
-        inquiries = items.ToList();
-        FilterInquiries();
-    }
-
-    private void FilterInquiries()
+    protected override void OnParametersSet()
     {
         filteredInquiries = string.IsNullOrEmpty(Status)
-            ? inquiries
-            : inquiries.Where(x => x.Status == Status).ToList();
+            ? Inquiries
+            : Inquiries.Where(x => x.Status == Status).ToList();
     }
 
     private static string GetPreview(string message)
@@ -77,9 +69,4 @@
     };
 
     private static string GetStatusLabel(string status) => InquiryStatusMapper.Labels.GetValueOrDefault(status, status);
-
-    protected override async Task OnParametersSetAsync()
-    {
-        FilterInquiries();
-    }
 }