fix: improve 404 page layout with responsive centering

Update 404 error page to use Bootstrap grid classes for better responsive
centering and constrained width on larger screens.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <[email protected]>

Author: markdumay

layouts/404.html

@@ -2,7 +2,7 @@
     {{ $base := partial "utilities/GetStaticURL" (dict "url" "/") }}
     <section class="container-fluid p-0 section-cover d-flex align-items-center">
         <div class="container-xxl my-auto h-100">
-            <div class="text-center">
+            <div class="col-12 col-sm-8 col-md-6 text-center mx-auto">
                 <span class="text-secondary fw-bold">
                     {{ partial "assets/icon.html" (dict "icon" "fa face-frown fa-10x") }}
                     <p class="display-1 mt-3 fw-bold">404</p>