Delete the local shared/signing package (WebhookSigner, WebhookVerifier,
WebhookSecret, WebhookVerificationException) and use core
com.kingsrook.qqq.backend.core.utils.webhooks from QQQ 4.1.0-RC.5.
Delivery signing, inbound verification and secret generation and rotation
all go through core. The wire format is unchanged: same headers, v1,
prefix, whsec_ secrets and timestamp tolerance. Endpoints, secret storage
and delivery stay in this qbit.
Refs QRun-IO/qqq#1160 (this repo has issues disabled), architecture review
QRun-IO/qqq#1150 finding F11.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>