Write the showcase examples' layout tags as an application does

Plan step 38 review: nine sections' examples wrapped their components
in <x-livewire-material::stack>, ::row and ::grid (148 tags) beside an
unprefixed <x-button>, while bars, containment and the layout pages
wrote <x-stack>. The code sample is what an application copies, and
the example component rewrites only unprefixed tags to a configured
prefix, so the namespaced ones taught a second form and escaped it.
Every example now writes <x-stack>, <x-row> and <x-grid>; a test
rejects a namespaced tag inside an example heredoc.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Qwx5USif3wFFmxtHg5U1g9

resources/views/showcase/sections/data.blade.php

@@ -35,10 +35,10 @@
             </div>
             BLADE,
         'Pagination' => <<<'BLADE'
-            <x-livewire-material::stack gap="space300">
+            <x-stack gap="space300">
                 {{ (new \Illuminate\Pagination\LengthAwarePaginator(range(1, 10), 95, 10, 3, ['path' => '#data']))->links() }}
                 {{ (new \Illuminate\Pagination\Paginator(range(1, 11), 10, 2, ['path' => '#data']))->links() }}
-            </x-livewire-material::stack>
+            </x-stack>
             BLADE,
     ];
 @endphp