Custom domains: claim, verify, then activate

Moving an address you already serve onto Forumulate no longer has a moment where neither side answers it.

Changed

Verification and activation are separate steps. POST …/domains/{domainId}/verify with {"activate": false} proves you own the address without moving any traffic: the domain reads verified: true, active: false, and your own application keeps serving it. Prepare your side, then POST …/domains/{domainId}/activate switches the traffic. A verify with no body still verifies and activates in one step, as before.

setup.mode gained pending. GET …/domains/{domainId}/setup answers pending for a domain that is verified but not yet activated, or activated moments ago while routing settles — rather than reporting it as served.

See Custom domains.