Bound a text field's width from medium

M3 § Text Fields, Behaviour: compact may let a field span full width, but
medium and expanded must bound it — "never let it span the full width of a
large screen". Nothing in the package capped a field (plan step 24, audit
docs/audits/m3-alignment/inputs.md § Missing). From `medium` a field now stops
at 40rem — the site names no number, so the header says where this one comes
from — which a `max-w-*` class beats and `full` takes off. The search bar
already carries M3's own 720px.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Qwx5USif3wFFmxtHg5U1g9

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

@@ -41,6 +41,14 @@
                 </div>
             </div>
             BLADE,
+        'Width at medium and above' => <<<'BLADE'
+            <div class="w-full space-y-4">
+                {{-- M3: never let a text field span the full width of a large screen. From medium it stops at 40rem. --}}
+                <x-input label="Bounded, the default" hint="No wider than 40rem from medium, however wide the pane is" />
+                <x-input label="Narrower" class="max-w-xs" hint="A max-w-* class from the call site wins" />
+                <x-input label="The width of the pane" full icon="search" hint="`full` takes the bound off — for a search row or an editor" />
+            </div>
+            BLADE,
         'Character counter' => <<<'BLADE'
             <div class="grid w-full gap-6 medium:grid-cols-2">
                 <div class="grid content-start gap-4">