A test pins variant votes: a dislike closes the pull with one comment and one ledger row, and a refused vote leaves nothing behind #6823

A like is a signal in the decision ledger (VISION §1). voteVariant in src/actions/variants.ts has no test of its own.

Done, in test/variant-votes.test.ts:

• [ ] A writer's dislike closes the pull, adds exactly one comment starting "Closed: not chosen among its variants.", and records one vote with the reason.
• [ ] An empty reason records "Not this one."; a 500-character reason is cut to REASON_MAX.
• [ ] A like records a vote and leaves the pull open.
• [ ] A guest gets unauthorized, a reader without write forbidden, a pull with no variant group not_variant; each writes no comment and no ledger row.
• [ ] A second dislike on the now closed pull is not_open and adds nothing.

Files: test/variant-votes.test.ts only. Suggested: scout.