Add buttons, menus and the rest of M3 Expressive's actions

<x-button> (label buttons, icon buttons and toggles in five sizes, with
filled, tonal, outlined, elevated and text variants in any colour role),
<x-tooltip>, <x-menu> with items, groups and separators, <x-button-group>,
<x-group> as a connected button group, <x-split-button>, <x-fab>,
<x-fab-menu> and <x-loading>. Sizes, colours and shapes come from
androidx Compose Material 3's tokens; the loading indicator ports its
Morph into SVG + SMIL.

Menus follow WAI-ARIA's menu button pattern on popovers placed by CSS
anchor positioning. Browser tests run in Chromium, Firefox and WebKit.
The showcase fetches the icon names on demand: inlined, they tripped
Pest's test server into HTTP 431s under Firefox.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01V9NnLxnPp8vaaurb3Z1MFy

resources/views/showcase/components/example.blade.php

@@ -0,0 +1,19 @@
+{{-- One showcase example: the Blade in `code`, rendered, with the source beside it — one string,
+     so what is shown and what is written can never disagree. --}}
+
+@props(['title' => null, 'code', 'stack' => false])
+
+<div class="space-y-4 rounded-corner-lg bg-surface-container p-4">
+    @if ($title)
+        <h3 class="type-title-md">{{ $title }}</h3>
+    @endif
+
+    <div @class(['flex flex-wrap items-center gap-4' => ! $stack, 'space-y-4' => $stack])>
+        {!! \Illuminate\Support\Facades\Blade::render($code) !!}
+    </div>
+
+    <details>
+        <summary class="w-fit cursor-pointer rounded-corner-xs type-label-md text-on-surface-variant focus-ring">Blade</summary>
+        <pre class="mt-2 overflow-x-auto rounded-corner-sm bg-surface-container-highest p-3 type-body-sm"><code>{{ trim($code) }}</code></pre>
+    </details>
+</div>