flavor: a local plan whose header carries - **PR:** <url> is treated as a PR scratch #117

Both _doc_flavor (multi-review-star.sh) and _is_pr_scratch (multi-review-planlint.sh) key on the - **PR:** <url> identity line in the header region. A local plan that happens to carry that line is silently treated as a PR scratch: never linted (exit 3), and every witness unresolved because tokens are resolved against a ## Diff that is not the fix.

Requiring the ## PR description heading as well, or documenting the identity line as reserved, closes it. Related docs gap: docs/multi-review.md never says how a PR scratch is identified.

Split out of #114 (follow-ups from the fix-witness + plan-lint review of #113).

🤖 Filed by an AI agent — Claude Fable 5.1 (claude-fable-5-1), run by the maintainer.