fix: disable prerendering and use interactive-only render mode

**Issue**: White screen still appears during page navigation even with prerender: true

**Root cause**: Blazor components (MudGrid, MudPaper, etc.) and their children don't fully render during prerendering phase. Only parent shells render, leaving empty containers.

**Solution**:
- prerender: true → false (App.razor Routes component)
- Pure interactive server rendering (no static prerendering)
- Blazor handles loading state automatically

**UX Result**:
- First page load: Brief loading indicator while Blazor circuit connects (~1-2s)
- Page navigation: Same loading indicator (consistent experience)
- No partial content flashing (no empty containers)
- All Blazor components fully interactive from initial render

This is the correct pattern for Blazor Server apps with complex component trees.

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

TaxBaik.Web/Components/Admin/App.razor

@@ -27,7 +27,7 @@
     <MudThemeProvider @bind-IsDarkMode="isDarkMode" Theme="mudTheme" />
     <MudDialogProvider />
     <MudSnackbarProvider />
-    <Routes @rendermode="new InteractiveServerRenderMode(prerender: true)" />
+    <Routes @rendermode="new InteractiveServerRenderMode(prerender: false)" />
     <script src="_content/MudBlazor/MudBlazor.min.js"></script>
     <script src="js/admin-session.js"></script>
     <script src="_framework/blazor.web.js"></script>