Rename <x-choices>'s data-active hook to data-md-active

Review leftover (plan step 36): the searchable list's highlighted-row
hook was still the plain pre-Phase-F name, in both the view's binding
and its scroll-into-view lookup and the shared rule in menu.css that
paints it. No test named it directly, so none needed a change.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Qwx5USif3wFFmxtHg5U1g9

resources/views/components/choices.blade.php

@@ -128,7 +128,7 @@
                 this.open = false;
             },
             reveal() {
-                this.$refs.list.querySelector('[data-active]')?.scrollIntoView({ block: 'nearest' });
+                this.$refs.list.querySelector('[data-md-active]')?.scrollIntoView({ block: 'nearest' });
             },
         }"
         @if ($model === null) x-modelable="value" @endif
@@ -185,7 +185,7 @@
                     x-bind:id="'{{ $id }}-option-' + index"
                     x-bind:aria-selected="(option.value === value).toString()"
                     x-bind:aria-disabled="option.disabled ? 'true' : null"
-                    x-bind:data-active="index === active ? '' : null"
+                    x-bind:data-md-active="index === active ? '' : null"
                     x-on:mousedown.prevent="choose(option)"
                     x-on:mousemove="active = index"
                     data-md-field-option