Fix 404 on _framework assets in production deploy

Blazor framework assets (blazor.web.js) under _framework are served via
the static-asset endpoints manifest, not physical wwwroot files. Plain
UseStaticFiles only serves physical files, so published deployments
returned 404 for blazor.web.js (worked in dev via the dev-time static
web assets provider). Switch to MapStaticAssets, which reads the
endpoints manifest shipped with publish.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Program.cs

@@ -207,7 +207,7 @@ if (!app.Environment.IsDevelopment())
 // Re-execute unmatched (404) requests into the branded not-found page
 app.UseStatusCodePagesWithReExecute("/not-found");
 
-app.UseStaticFiles();
+app.MapStaticAssets();
 app.UseAuthentication();
 app.UseAuthorization();
 app.UseAntiforgery();