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/components/menu-group.blade.php

@@ -0,0 +1,9 @@
+{{-- A labelled group of items in an `<x-menu>`: "Sort by", "Share with". --}}
+
+@props(['label'])
+
+<div role="group" aria-label="{{ $label }}" {{ $attributes->class('py-1 first:pt-0 last:pb-0') }}>
+    <div aria-hidden="true" class="px-3 pt-2 pb-1 type-label-lg text-on-surface-variant">{{ $label }}</div>
+
+    {{ $slot }}
+</div>