Implements ReprovisionNotifyHost to migrate a project's email sending
from an old notify host to a new one (e.g., from project-name-based to
slug-based host). Preserves the project's notify account and send key.
- Adds ReprovisionNotifyHost to port.NotifyProvisioner interface
- Implements revokeHostAccess on notifyAdminAPI + adminClient
- Implements Provisioner.ReprovisionNotifyHost (12-step migration)
in provisioner_reprovision.go (split to keep provisioner.go < 500 lines)
- Adds NotifyHandler.Reprovision handler (POST /notify/reprovision)
- Updates OpenAPI spec with reprovision endpoint
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
