Project Agent Discovery

Turn the interview into real objects: an ICP, a persona, AND A CAMPAIGN.

Takes no body. The campaign is the part that surprises people, so it is said plainly: this CREATES a campaign and provisions its Work channel. It does not SEND anything - the campaign sits there for a human to launch - which is why this is a write and not an external operation.

IDEMPOTENT: the projection is idempotent by object name, and the build is claim-fenced, so calling twice updates the same ICP and returns the same campaign rather than minting a second one.

PARTIAL SUCCESS IS A REAL OUTCOME. A refused build does not fail the projection, because the ICP and persona are committed by the time the build runs and reporting the whole call as failed would send someone to re-run a projection that worked. Read campaign.ok in the body; a blocked build names what is still open rather than counting it.