Introduce a DomainAvailabilityWatch entity (model, storage, usecase and
REST endpoints) letting a user track a domain they do not own and get
notified the moment it becomes available for registration. A dedicated
domain_availability checker reads WHOIS/RDAP via pkg/domaininfo and inverts
the status (OK while registered, Crit once free) so the existing dispatcher
fires exactly once on the transition. The scheduler enumerates watches and
enqueues the check, carrying the watch id in CheckTarget.DomainId; autofill
and notification payloads fall back to the watch store to resolve the name.
Watches are included in per-user backup/restore. The web UI adds an
availability watchlist page and navigation entry.
Pierre-Olivier Mercier
5ccf81173f