WorkplanDomain

One WorkPlan-able DomainAgent, for the domain-centric create picker.

Field	Type	Description
`domain_key`required	`string`	Canonical domain key — pass straight into POST /workstreams/jobs {domain}. Round-trips through PERSONA_REGISTRY.for_workstream() to this DomainAgent's goal_template (e.g. 'ita_2007_eis', 'vat_return').
`label`required	`string`	Human-readable agent name for the picker.
`description`required	`string`	What this DomainAgent produces.
`goal_template`required	`string`	The agent's goal template (the create flow's default goal).