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/App.razor

@@ -24,7 +24,7 @@
             <span>배포 또는 서버 재시작 중이면 잠시 후 자동으로 새로고침됩니다.</span>
         </div>
     </div>
-    <div id="blazor-loading" class="blazor-loading-overlay">
+    <div id="blazor-loading" class="blazor-loading-overlay show">
         <div class="blazor-loading-spinner">
             <div class="spinner"></div>
             <p>로드 중...</p>

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();
-    }
 }

TaxBaik.Web/Components/Admin/Layout/MainLayout.razor

@@ -1,4 +1,7 @@
 @inherits LayoutComponentBase
+@inject NavigationManager Navigation
+@inject IJSRuntime JS
+@implements IDisposable
 
 <MudLayout Class="admin-shell">
     <MudAppBar Elevation="0" Class="admin-topbar">
@@ -73,8 +76,23 @@
     private bool expandedCustomerGroup = true;
     private bool expandedWebsiteGroup = false;
 
+    protected override void OnInitialized()
+    {
+        Navigation.LocationChanged += OnLocationChanged;
+    }
+
+    private void OnLocationChanged(object? sender, LocationChangedEventArgs args)
+    {
+        _ = InvokeAsync(() => JS.InvokeVoidAsync("taxbaikAdminSession.showLoading"));
+    }
+
     private void ToggleDrawer()
     {
         drawerOpen = !drawerOpen;
     }
+
+    public void Dispose()
+    {
+        Navigation.LocationChanged -= OnLocationChanged;
+    }
 }

TaxBaik.Web/Components/Admin/Pages/Inquiries/InquiryList.razor

@@ -1,7 +1,7 @@
 @page "/admin/inquiries"
 @attribute [Authorize]
-@using TaxBaik.Domain.Interfaces
-@inject IInquiryRepository InquiryRepository
+@using TaxBaik.Web.Services
+@inject IInquiryBrowserClient InquiryClient
 
 <PageTitle>문의 관리</PageTitle>
 
@@ -13,25 +13,44 @@
     </div>
 </section>
 
-<MudPaper Class="admin-surface" Elevation="0">
-<MudTabs Rounded="true" Elevation="0" Class="admin-tabs">
-    <MudTabPanel Text="전체">
-        <InquiryTable Status="" />
-    </MudTabPanel>
-    <MudTabPanel Text="신규">
-        <InquiryTable Status="new" />
-    </MudTabPanel>
-    <MudTabPanel Text="상담중">
-        <InquiryTable Status="consulting" />
-    </MudTabPanel>
-    <MudTabPanel Text="계약완료">
-        <InquiryTable Status="contracted" />
-    </MudTabPanel>
-    <MudTabPanel Text="거절">
-        <InquiryTable Status="rejected" />
-    </MudTabPanel>
-    <MudTabPanel Text="종결">
-        <InquiryTable Status="closed" />
-    </MudTabPanel>
-</MudTabs>
-</MudPaper>
+@if (isLoading)
+{
+    <MudProgressCircular Indeterminate="true" Class="ma-4" />
+}
+else
+{
+    <MudPaper Class="admin-surface" Elevation="0">
+    <MudTabs Rounded="true" Elevation="0" Class="admin-tabs">
+        <MudTabPanel Text="전체">
+            <InquiryTable Inquiries="allInquiries" Status="" />
+        </MudTabPanel>
+        <MudTabPanel Text="신규">
+            <InquiryTable Inquiries="allInquiries" Status="new" />
+        </MudTabPanel>
+        <MudTabPanel Text="상담중">
+            <InquiryTable Inquiries="allInquiries" Status="consulting" />
+        </MudTabPanel>
+        <MudTabPanel Text="계약완료">
+            <InquiryTable Inquiries="allInquiries" Status="contracted" />
+        </MudTabPanel>
+        <MudTabPanel Text="거절">
+            <InquiryTable Inquiries="allInquiries" Status="rejected" />
+        </MudTabPanel>
+        <MudTabPanel Text="종결">
+            <InquiryTable Inquiries="allInquiries" Status="closed" />
+        </MudTabPanel>
+    </MudTabs>
+    </MudPaper>
+}
+
+@code {
+    private bool isLoading = true;
+    private IReadOnlyList<Domain.Entities.Inquiry> allInquiries = [];
+
+    protected override async Task OnInitializedAsync()
+    {
+        var (items, _) = await InquiryClient.GetPagedAsync(1, 200);
+        allInquiries = items.ToList();
+        isLoading = false;
+    }
+}

TaxBaik.Web/wwwroot/css/admin.css

@@ -1391,6 +1391,23 @@ textarea:focus-visible {
 
 #blazor-loading.show {
   display: flex;
+  animation: overlayFadeIn 0.15s ease-out;
+}
+
+@keyframes overlayFadeIn {
+  from { opacity: 0; }
+  to   { opacity: 1; }
+}
+
+/* Page content fade-in on each route mount */
+.admin-page-hero,
+.admin-login-page {
+  animation: adminPageIn 0.25s ease-out;
+}
+
+@keyframes adminPageIn {
+  from { opacity: 0; transform: translateY(6px); }
+  to   { opacity: 1; transform: translateY(0); }
 }
 
 .blazor-loading-overlay {

TaxBaik.Web/wwwroot/js/admin-session.js

@@ -4,6 +4,7 @@ window.taxbaikAdminSession = {
             'admin-login-route',
             window.location.pathname.toLowerCase().endsWith('/admin/login'));
     },
+
     clearAuthToken: function () {
         try {
             localStorage.removeItem('auth_token');
@@ -11,54 +12,73 @@ window.taxbaikAdminSession = {
             // Ignore storage errors; redirect still recovers the session.
         }
     },
+
+    showLoading: function () {
+        const overlay = document.getElementById('blazor-loading');
+        if (!overlay) return;
+
+        // Start observer FIRST so it catches the mutation that brings new content in.
+        if (window._taxbaikLoadingObserver) {
+            window._taxbaikLoadingObserver.disconnect();
+        }
+        window._taxbaikLoadingObserver = new MutationObserver(function () {
+            const pageReady =
+                document.querySelector('.admin-page-hero') !== null ||
+                document.querySelector('.admin-login-page') !== null;
+            if (pageReady) {
+                window.taxbaikAdminSession.hideLoading();
+            }
+        });
+        window._taxbaikLoadingObserver.observe(document.body, {
+            childList: true,
+            subtree: true
+        });
+
+        // Show overlay after observer is active.
+        overlay.classList.add('show');
+
+        // Safety fallback: hide after 3 seconds regardless.
+        if (window._taxbaikLoadingTimeout) {
+            clearTimeout(window._taxbaikLoadingTimeout);
+        }
+        window._taxbaikLoadingTimeout = setTimeout(function () {
+            window.taxbaikAdminSession.hideLoading();
+        }, 3000);
+    },
+
+    hideLoading: function () {
+        const overlay = document.getElementById('blazor-loading');
+        if (overlay) {
+            overlay.classList.remove('show');
+        }
+
+        if (window._taxbaikLoadingTimeout) {
+            clearTimeout(window._taxbaikLoadingTimeout);
+            window._taxbaikLoadingTimeout = null;
+        }
+
+        if (window._taxbaikLoadingObserver) {
+            window._taxbaikLoadingObserver.disconnect();
+            window._taxbaikLoadingObserver = null;
+        }
+    },
+
     watchReconnect: function () {
         window.taxbaikAdminSession.syncRouteClass();
         window.addEventListener('popstate', window.taxbaikAdminSession.syncRouteClass);
 
-        // Hide loading indicator after Blazor initializes
-        const loadingOverlay = document.getElementById('blazor-loading');
-        if (loadingOverlay) {
-            const hideLoading = () => {
-                if (loadingOverlay.classList.contains('show')) {
-                    loadingOverlay.classList.remove('show');
-                }
-            };
-
-            // Method 1: Hide after 3 seconds (guaranteed timeout)
-            setTimeout(hideLoading, 3000);
-
-            // Method 2: Hide when Blazor components appear (faster if available)
-            const observer = new MutationObserver(() => {
-                const mudElements = document.querySelectorAll('[class*="mud-"]').length;
-                if (mudElements > 10) {
-                    hideLoading();
-                    observer.disconnect();
-                }
-            });
-            observer.observe(document.body, {
-                childList: true,
-                subtree: true,
-                attributes: true
-            });
-
-            // Method 3: Hide when page is interactive
-            document.addEventListener('readystatechange', () => {
-                if (document.readyState === 'interactive' || document.readyState === 'complete') {
-                    setTimeout(hideLoading, 500);
-                }
-            });
-        }
+        // Show loading on initial page load — overlay has 'show' from HTML,
+        // but we still need to set up the observer to detect when to hide it.
+        window.taxbaikAdminSession.showLoading();
 
         const modal = document.getElementById('components-reconnect-modal');
-        if (!modal) {
-            return;
-        }
+        if (!modal) return;
 
-        const reloadOnRejectedCircuit = () => {
+        const reloadOnRejectedCircuit = function () {
             const className = modal.className || '';
             if (className.includes('components-reconnect-failed') ||
                 className.includes('components-reconnect-rejected')) {
-                window.setTimeout(() => window.location.reload(), 1500);
+                window.setTimeout(function () { window.location.reload(); }, 1500);
             }
         };