Verify webhook signatures

Receive and verify Adyen payment webhooks

This skill shows an agent how to build an endpoint that receives Adyen standard notifications and checks their signatures. The signature covers a colon-joined list of specific fields rather than the raw body and uses a hex-decoded key, and the skill spells out that order with Node and Python examples. The endpoint must answer with the literal text [accepted] and a 200 status, or Adyen retries. It also covers handling payment events such as authorisation, refund and chargeback.