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/progress.blade.php

@@ -31,15 +31,15 @@
             <x-progress value="55" wavy color="info" label="Info" />
             BLADE,
         'Following a value in the browser (bind)' => <<<'BLADE'
-            <x-livewire-material::stack gap="space300" x-data="{ progress: 30 }">
+            <x-stack gap="space300" x-data="{ progress: 30 }">
                 <x-button label="Set a random value" variant="tonal" x-on:click="progress = Math.round(Math.random() * 100)" />
                 <x-progress bind="progress" label="Bound" />
                 <x-progress bind="progress" wavy label="Bound wavy" />
-                <x-livewire-material::row gap="space300">
+                <x-row gap="space300">
                     <x-progress bind="progress" circular label="Bound circular" />
                     <x-progress bind="progress" circular wavy label="Bound circular wavy" />
-                </x-livewire-material::row>
-            </x-livewire-material::stack>
+                </x-row>
+            </x-stack>
             BLADE,
     ];