MCNS returns records wrapped in {"records": [...]} envelope with
uppercase field names (ID, Name, Type, Value), not bare arrays
with lowercase fields.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
Add DNSRegistrar that creates/updates/deletes A records in MCNS
during deploy and stop. When a service has routes, the agent ensures
an A record exists in the configured zone pointing to the node's
address. On stop, the record is removed.
- Add MCNSConfig to agent config (server_url, ca_cert, token_path,
zone, node_addr) with defaults and env overrides
- Add DNSRegistrar (internal/agent/dns.go): REST client for MCNS
record CRUD, nil-receiver safe
- Wire into deploy flow (EnsureRecord after route registration)
- Wire into stop flow (RemoveRecord before container stop)
- 7 new tests, make all passes with 0 issues
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
