Easy!Appointments has unauthenticated customer PII disclosure on booking reschedule page

Easy!Appointments is a self hosted appointment scheduler. In versions up to and including 1.5.2, 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. Version 1.6.0 contains a patch.