Move the select's rules out of the field into select.css

<x-select> marks its field root data-md-select, and what a <select>
changes in the field — covering the whole box, the customizable
select's closed button, the focused look and turned arrow while open —
moves from field.css to components/select.css (plan step 36). The open
list stays in menu.css until the menu leaves Tailwind.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Qwx5USif3wFFmxtHg5U1g9

resources/views/components/select.blade.php

@@ -10,7 +10,8 @@
      `options` as a list of `['id' => …, 'name' => …]` (`'disabled' => true` greys one out),
      `option-value` and `option-label` to read other keys, and a `placeholder` that becomes the
      first option, valued `placeholder-value` (empty by default). Or pass `<option>`s in the slot.
-     `label`, `hint`, `icon`, `variant`, `size`. --}}
+     `label`, `hint`, `icon`, `variant`, `size`. The field's root carries `data-md-select`; what a
+     select changes in the field's chrome is resources/css/components/select.css. --}}
 
 @props([
     'label' => null,
@@ -35,7 +36,7 @@
     $fieldIconSize = ['sm' => 20, 'xs' => 16][$size] ?? 24;
 @endphp
 
-<x-livewire-material::field :$id :$label :$hint :hint-class="$hintClass" :$messages :$icon :$size :$variant floated :class="$attributes->get('class')">
+<x-livewire-material::field :$id :$label :$hint :hint-class="$hintClass" :$messages :$icon :$size :$variant floated :class="$attributes->get('class')" data-md-select>
     <select
         {{ $attributes->except(['class', 'id']) }}
         id="{{ $id }}"