Variable PAYPAL_WEBHOOK_HEADER_NAMES`Const`

PAYPAL_WEBHOOK_HEADER_NAMES: readonly [
    "paypal-transmission-id",
    "paypal-transmission-time",
    "paypal-cert-url",
    "paypal-auth-algo",
    "paypal-transmission-sig",
] = ...

PayPal webhook verification is a postback: the adapter POSTs the delivery headers plus the raw event back to /v1/notifications/verify-webhook-signature and PayPal answers SUCCESS/FAILURE. No local X.509 handling — edge-clean.