feat: outgoing webhooks

Owners and admins can point a project at other systems: a signed JSON
POST (HMAC-SHA256 of the body) when tickets, comments, releases or sprints
change, filtered by event or family. Deliveries are retried a couple of
times, the last one is shown, and a ping can be sent from the settings.
Private addresses are refused unless WEBHOOKS_ALLOW_PRIVATE is set.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

libs/api/tracker/application/src/lib/ports/index.ts

@@ -24,3 +24,4 @@ export * from './saved-filters.repository';
 export * from './find-sprints.repository';
 export * from './upsert-materialized-sprint.repository';
 export * from './git-integrations.repository';
+export * from './outgoing-webhooks.repository';