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/components/field.blade.php

@@ -21,6 +21,10 @@
      "Character count, 5/20", M3's own label, from a polite region a second after typing stops rather
      than on every keystroke, which would talk over the typing.
 
+     From `medium` the field is no wider than 40rem, because M3 asks that a text field never span
+     the full width of a large screen (§ Text Fields, Behaviour); a `max-w-*` class from the call
+     site beats that, and `full` takes it off altogether.
+
      `class` from the call site lands on the outermost element, never the control, so a margin or
      a width is safe here. --}}
 
@@ -38,6 +42,7 @@
     'floated' => false,
     'mono' => false,
     'counter' => null,
+    'full' => false,
 ])
 
 @php
@@ -58,6 +63,7 @@
     @if ($messages !== []) data-invalid @endif
     @if ($floated) data-floated @endif
     @if ($mono) data-mono @endif
+    @if ($full) data-full @endif
 >
     <div class="field-box">
         @if ($icon)