- UpdateDnsRecords Action: controller method now one-liner, all DNS
logic in Action with activity logging and edit lock.
- Prometheus metrics at /v1/metrics: chain_height, alias_count,
claims_pending, dns_tickets, gateways_live. Grafana-ready.
- ValidateJsonRequest middleware: enforces application/json on POST,
64KB body size limit. Applied to all /v1/* API routes.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
