Add the Material 3 Expressive foundation

Colour, shape, type, elevation and motion as tokens and Tailwind
utilities; `php artisan material:scheme`, which generates an app's colour
roles with Google's material-color-utilities (spec 2025); the theme head
script with light, dark and system and its Alpine store; Google Sans Flex;
every Material Symbol (4,135, outlined and filled) drawn by <x-icon>
without blade-icons; all 35 M3 Expressive shapes, ported from androidx, as
<x-shape>; the x-figure directive; the Toasts concern; DesignGuard for
applications' tests; and a showcase with every token, both themes side by
side and an icon search.

Colour utilities are `@theme inline`, so a section with its own
data-theme repaints; without it they resolve once on :root.

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

tests/Feature/ShowcaseTest.php

@@ -30,3 +30,15 @@ it('does not mount the showcase when disabled', function () {
 
     $this->get('/material')->assertNotFound();
 });
+
+it('serves a symbol for the icon search', function () {
+    $this->get('/material/symbols/filled/favorite.svg')
+        ->assertOk()
+        ->assertHeader('Content-Type', 'image/svg+xml')
+        ->assertSee('viewBox="0 -960 960 960"', false);
+});
+
+it('answers 404 for a symbol or style that does not exist', function () {
+    $this->get('/material/symbols/outlined/not_a_symbol_at_all.svg')->assertNotFound();
+    $this->get('/material/symbols/sharp/favorite.svg')->assertNotFound();
+});