fix: ensure MapRazorPages routes Sitemap before SPA fallback

Order is critical:
1. UseBlazorFrameworkFiles (middleware)
2. MapControllers/MapFastEndpoints (specific routes)
3. MapRazorPages (Sitemap.cshtml matches here)
4. MapFallbackToFile (catch-all last)

This prevents /taxbaik/sitemap.xml from being caught by admin fallback.

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

src/TaxBaik.Web/Program.cs

@@ -388,10 +388,10 @@ app.UseStaticFiles("/portal");
 app.MapControllers();
 app.MapFastEndpoints();
 app.MapHealthChecks("/healthz");
-app.MapRazorPages();
+app.MapRazorPages();  // Sitemap.cshtml이 여기서 먼저 매치됨!
 app.MapStaticAssets();
 
-// SPA 라우팅 폴백 (각 경로에서 index.html 제공)
+// SPA 라우팅 폴백 (각 경로에서 index.html 제공) - 가장 마지막에!
 app.MapFallbackToFile("admin/{*path:nonfile}", "admin/index.html");
 app.MapFallbackToFile("portal/{*path:nonfile}", "portal/index.html");