Replace URL token auth with the official webhook secret signature check.
Add SETUP.md and separate TEST_TOKEN for the Postmark test endpoint.
Co-authored-by: Cursor <cursoragent@cursor.com>
Log partial-payment decisions and email results to stdout for Portainer
logs; DEBUG enables full webhook payload tracing. Document BTCPay payload
and shutdown steps in WEBHOOK.md.
Co-authored-by: Cursor <cursoragent@cursor.com>
Support docker exec and a secured /test-email endpoint to verify email
delivery before wiring up the BTCPay webhook.
Co-authored-by: Cursor <cursoragent@cursor.com>