Fix duplicate Alpine + broken entangle in setup wizard

1. app.js was importing and starting Alpine manually, but Livewire 3/4
   already bundles Alpine. Two instances meant $wire magic was unavailable.
   Now app.js just registers the focus plugin via Livewire's alpine:init hook.

2. Wizard x-data used @entangle which compiled to the old
   window.Livewire.find(id).entangle() syntax. Replaced with $wire getters
   which is the canonical Livewire 3+ approach.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

resources/js/app.js

-import Alpine from 'alpinejs';
 import focus from '@alpinejs/focus';
 
-Alpine.plugin(focus);
-window.Alpine = Alpine;
-Alpine.start();
+document.addEventListener('livewire:init', () => {
+    Livewire.hook('alpine:init', ({ Alpine }) => {
+        Alpine.plugin(focus);
+    });
+});

resources/views/livewire/wizards/setup-wizard.blade.php

 <div x-data="{
-    currentStep: @entangle('currentStep'),
-    totalSteps: @entangle('totalSteps'),
+    get currentStep() { return $wire.currentStep },
+    get totalSteps() { return $wire.totalSteps },
     animating: false,
     direction: 'forward'
 }" class="space-y-8">