Initial commit — Parker County Slingshot Rentals booking site

Full booking system with Square card-on-file, 10-step booking flow,
pre-departure checklist, and Mailjet email integration.

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

admin/logout.php

@@ -0,0 +1,7 @@
+<?php
+// admin/logout.php
+require_once __DIR__ . '/../config.php';
+unset($_SESSION['pcs_admin']);
+session_destroy();
+header('Location: /admin/login.php');
+exit;