#4373 serve: a capability probe answered by a follower does not speak for the leader that handles the forwarded request

The CLI checks server.version capabilities before sending a request an older serve would mishandle: literal-inputs before [HOST-1], resume-from-job before workflow.resume, and (from swamp-club#4370) schedule-catch-up before workflow.trigger.set. server.version is in FOLLOWER_READ_REQUESTS (src/serve/follower_requests.ts), so a follower answers it with its own capabilities, while [HOST-1], workflow.resume and workflow.trigger.set are in FOLLOWER_FORWARDED_REQUESTS and run on the leader. During a rolling upgrade where the follower is newer than the leader, the probe passes and the older leader then ignores the field: literalInputs is dropped and the inputs are evaluated as expressions, fromJob is dropped and the step resets in every job, catchUp is dropped and the override is saved without it. Possible fix: have a follower intersect its capabilities with the leader's (from the leader link) in its server.version reply, or have the leader re-check the capability on forwarded requests and refuse fields it cannot honour. Tests: a follower in front of a leader without the capability does not advertise it.