Let the release-readiness gate pass on the release commit

[NSchatz]

The release pipeline runs pnpm test on Changesets' version commit before it publishes. That commit moves package.json to 0.1.0 and consumes every pending changeset, and test/scripts/release-readiness.test.ts asserted the pre-bump state only, so it would have stopped the 0.1.0 publish in the Verify step.

Repro (before this change)

On a copy of main at 8871a11:

pnpm install --frozen-lockfile
pnpm run version       # changeset version + sync-version: package.json -> 0.1.0, changesets consumed
# commit that result locally, as the Version Packages PR would
pnpm exec vitest run test/scripts/release-readiness.test.ts
# 6 failed | 27 passed: "is not empty", "is measured against the version this audit was
# taken on", "carries at least one minor and no major", "resolves the package to the
# prepared version", "classifies the LIVD catalog changeset as minor",
# "accounts for every pending changeset"

The change

The gate recognizes one state, the release commit: the manifest at the prepared version AND nothing pending (isReleaseCommit). Only there are the two describes that read the pending set skipped.

• A premature bump (0.1.0 with the set still pending) and a set deleted without a bump both still fail; each is pinned by a synthetic case.
• The surface and certification checks run in every state, so the release publishes exactly what the record certifies.
• The first changeset written after the release still reds the gate, as its header always said.

Proof after the change

Same simulation on this branch: pnpm typecheck && pnpm lint && pnpm test && pnpm build && pnpm attw exits 0 on the simulated version commit (72 files, 1264 passed, 11 skipped). On the branch itself the gate file passes (34 tests).

No change under src/.

https://claude.ai/code/session_01U24bnHKNxQWMxmfN7ny7w9