feat: add Weeztix OAuth, coupon codes, and Mailwizz mapping

Implement Weeztix integration per documentation: database config and
subscriber coupon_code, OAuth redirect/callback, admin setup UI with
company/coupon selection via AJAX, synchronous coupon creation on public
subscribe with duplicate and rate-limit handling, Mailwizz field mapping
for coupon codes, subscriber table and CSV export, and connection hint
on the pages list.

Made-with: Cursor

resources/views/admin/pages/index.blade.php

@@ -75,6 +75,12 @@
                                         @can('update', $page)
                                             <a href="{{ route('admin.pages.mailwizz.edit', $page) }}" class="text-indigo-600 hover:text-indigo-500">{{ __('Mailwizz') }}</a>
                                         @endcan
+                                        @can('update', $page)
+                                            <a href="{{ route('admin.pages.weeztix.edit', $page) }}" class="text-indigo-600 hover:text-indigo-500">{{ __('Weeztix') }}</a>
+                                            @if ($page->weeztixConfig?->is_connected)
+                                                <span class="text-xs font-medium text-emerald-600" title="{{ __('Weeztix verbonden') }}">●</span>
+                                            @endif
+                                        @endcan
                                         <button
                                             type="button"
                                             x-data="{ copied: false }"