fix: replace all native confirm() dialogs with styled modal macros

Migrated ~68 native browser confirm() calls across 74 files to use the
project's confirm_modal/confirm_modal_dynamic Jinja2 macros, providing
consistent styled confirmation dialogs instead of plain browser popups.

Modules updated: core, tenancy, cms, marketplace, messaging, billing,
customers, orders, cart. Uses danger/warning/info variants and
double-confirm pattern for destructive delete operations.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

app/modules/billing/templates/billing/store/billing.html

@@ -1,7 +1,7 @@
 {# app/templates/store/billing.html #}
 {% extends "store/base.html" %}
 {% from 'shared/macros/headers.html' import page_header %}
-{% from 'shared/macros/modals.html' import modal_simple %}
+{% from 'shared/macros/modals.html' import modal_simple, confirm_modal_dynamic %}
 
 {% block title %}Billing & Subscription{% endblock %}
 
@@ -308,7 +308,7 @@
                                         <span x-text="addon.period_end ? `Renews ${formatDate(addon.period_end)}` : 'Active'"></span>
                                     </p>
                                 </div>
-                                <button @click="cancelAddon(addon)"
+                                <button @click="pendingCancelAddon = addon; showCancelAddonConfirm = true"
                                         class="px-3 py-1 text-sm font-medium text-red-600 bg-red-100 rounded-lg hover:bg-red-200 dark:bg-red-900/50 dark:text-red-400">
                                     Cancel
                                 </button>
@@ -355,6 +355,9 @@
     </div>
 </div>
 
+<!-- Cancel Add-on Confirm Modal -->
+{{ confirm_modal_dynamic('cancelAddonConfirm', 'Cancel Add-on', "'Are you sure you want to cancel ' + (pendingCancelAddon?.addon_name || 'this add-on') + '?'", 'cancelAddon(pendingCancelAddon)', 'showCancelAddonConfirm', 'Cancel Add-on', 'Keep', 'danger') }}
+
 <!-- Cancel Subscription Modal -->
 <div x-show="showCancelModal"
      x-transition:enter="transition ease-out duration-150"