CVE-2026-52837: Easy!Appointments has unauthenticated customer PII disclosure on booking reschedule page

The booking reschedule view at /index.php/booking/reschedule/{appointment_hash} (handled by Booking::index()) embeds the entire customer record as inline JavaScript (const vars = {... "customer_data": {...}, ...}) without authentication and without field whitelisting. Anyone in possession of the 12-character appointment_hash — which appears in plain text in reschedule emails, confirmation page URLs, and operator-side calendar links — can read every column of that customer’s row in the ea_users table.

Verified against v1.5.2 with a Docker reproduction; a single anonymous GET to the reschedule URL returns 13 customer fields including email, phone, full address, custom fields, timezone, language, LDAP DN, and id_roles.