add_organization_domain

Add one pending organization domain and issue its public TXT verification record. Live account read/write grant and org owner/admin required. Shared serializable cap check bounds the organization to 50 domains across browser/CLI/tools, inspecting at most 50 keys; no new index. Names use the existing normalizer. Existing names or a full organization return conflict; after a lost response read the domain list before retrying. No DNS lookup/change, provider credentials, verification, routing/sending, spend or receipt. Shared 20/min caller limit.