#3104 extension push: the undecided private-entitlement verdict still says the registry may start a trial at publish

Description

Since swamp-club PR 1278 (f26384f9) a trial starts only when its collective is created; marking an extension private no longer opens one. The CLI's private-entitlement check from Lab #1545 (swamp PR 2875) still describes the old door. For a free collective the registry reported with no trial, the dry run says:

Collective "@<slug>" is on the Free plan with no trial reported; the registry decides private publication at publish.

and the code comment and design text behind it say the registry "may start the collective's trial at publish". The real push is then refused by the registry with Private publication requires a paid plan or an active trial, and the CLI adds At sign-in the registry reported "@<slug>" on the Free plan with no trial reported. plus the upgrade page.

The verdict is not wrong, since the registry does decide, but the reason given to the author is stale: nothing will start a trial at publish, so the push will be refused. The check could fail outright for a free plan with no trial, or keep the undecided verdict with wording that says the push will be refused unless the collective is on a paid plan.

Steps to reproduce

1. Seed a team collective with no trial and no subscription (seed:collective without --trial-elapsed-days or --plan), sign in as its owner.
2. swamp extension push <manifest> --visibility private --dry-run --yes for an extension under that collective: the private-entitlement check is not-run with the wording above.
3. swamp extension push <manifest> --visibility private --yes: refused by the registry.

Environment

swamp 20261006.184908.0-sha.c4c1ed56 against swamp-club main at f26384f9. Observed while writing swamp-uat #552 (tests/cli/extension/push_visibility_test.ts), which asserts only the real push and not this wording.