Implement missing API endpoints

[JoshSEdwards]

Summary

• add health/status endpoints: ping/health/color/metrics_prometheus, get_status/update_status
• add zone endpoints: get_zone_details, list_zone_backend_ids, list_zone_changes_failure,
  list_deleted_zones
• add record set endpoints: get_record_set_count, list_record_set_change_history,
  list_record_set_changes_failure
• add ownership transfer helpers for record sets (request/approve/reject/cancel)
• add group endpoints: get_group_change, list_group_valid_domains
• add user endpoints: get_user, lock_user, unlock_user
• add unit tests for all new endpoints

Files Touched

• src/vinyldns/client.py, src/vinyldns/status.py
• src/vinyldns/zone.py, src/vinyldns/record.py, src/vinyldns/membership.py
• tests/test_health_status.py, tests/test_zone_extras.py
• tests/test_record_extras.py, tests/test_membership_extras.py, tests/test_users.py

Manual Test Checklist

Prereqs:

• VINYLDNS_HOST, VINYLDNS_ACCESS_KEY, VINYLDNS_SECRET_KEY set
• Admin creds for status update, user lock/unlock, ACL rules, batch review
• Sample IDs: zone_id, group_change_id, user_id/username, record set fqdn/type

Health & Monitoring:

• ping returns PONG
• health returns OK (no error)
• color returns blue or green
• metrics_prometheus returns non-empty text

Status:

• get_status returns processingDisabled, color, keyName, version
• update_status flips processingDisabled (admin)

Zone:

• list_zone_backend_ids returns non-empty list
• get_zone_details includes admin group ID/name
• list_deleted_zones returns expected entries
• list_zone_changes_failure returns entries (can be empty)

RecordSet:

• get_record_set_count returns integer
• list_record_set_change_history returns list for fqdn/type
• list_record_set_changes_failure returns entries (can be empty)
• ownership transfer request/approve/reject/cancel succeeds with valid record set and owner group
  IDs

Group:

• list_group_valid_domains returns entries
• get_group_change returns change details

User (admin):

• get_user returns id/username/groups
• lock_user returns Locked
• unlock_user returns Unlocked

Automated Tests

• python3 setup.py test

VDNS-250