fix: enable prerendering to eliminate white screen on page load

**Issue**: Pages show white screen briefly before rendering when navigating between pages

**Root cause**: prerender: false in Routes component meant pages weren't statically prerendered before Blazor interactive mode connected, causing delay

**Fix**:
- Changed prerender: false → prerender: true
- Added explicit MudDialogProvider and MudSnackbarProvider for prerendering support

**Result**: Pages now render immediately with initial HTML, Blazor interactivity attached after - no white screen flash

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

TaxBaik.Web/Components/Admin/App.razor

@@ -25,7 +25,9 @@
         </div>
     </div>
     <MudThemeProvider @bind-IsDarkMode="isDarkMode" Theme="mudTheme" />
-    <Routes @rendermode="new InteractiveServerRenderMode(prerender: false)" />
+    <MudDialogProvider />
+    <MudSnackbarProvider />
+    <Routes @rendermode="new InteractiveServerRenderMode(prerender: true)" />
     <script src="_content/MudBlazor/MudBlazor.min.js"></script>
     <script src="js/admin-session.js"></script>
     <script src="_framework/blazor.web.js"></script>