feat(gates): the changeset level follows the metadata protocol — a Metadata-protocol: line beside Clause-②:

Maintainer ruling A (2026-10-21): `minor` only when the metadata protocol is
added to, narrowed or changed in meaning; `patch` otherwise. The one reader
(`scripts/pm/clause2-line.mjs`) gains the sibling line, import-free, with the
`Clause-②:` reader byte-identical in behaviour. `check-changeset-no-major.mjs`
judges the level on the kind: a kind owes `minor` on a moved package, `none`
owes `patch` everywhere and may not move an authorable-surface/-defaults
baseline, `added` under `no` and `narrowed` without the `(narrowing)` arm are
contradictions, and an unread kind that decides the verdict is refused as
NOT MEASURED. Fixtures updated; a ruling-A battery added (floor 21 -> 22).

Claude-Session: https://claude.ai/code/session_01VsqhiSrBjB1wJfRNcHPeXN
Co-authored-by: Claude <noreply@anthropic.com>

Author: claude