#12 SiteDomainService.give_subdomain(app, label): one-click publish an app at
<slug>.<base> — primary Domain row + nginx vhost + (per-site mode) an auto-created,
guarded/logged A record. Endpoints: POST /domains/give-subdomain and
GET /domains/suggest-subdomain.
#14 GET /api/v1/dns/managed: every record ServerKit owns across all provider zones,
enriched with the app that triggered each (from the ownership ledger).
#13 inline propagation reuses the existing /dns/propagation/<domain> check.
Tests: test_dns_give_subdomain.py.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>