A deck chooses among sibling pulls: one card each, like or dislike recorded in the decision ledger, disliked ones closed with a reason #1410

Part of #587 (P1 Feed), the second piece of #1051; waits for #1409 (the group id).

Done looks like.

• [ ] A page for a variant group shows one card per open sibling, reusing the look card (phone and desktop pictures) and the preview card.
• [ ] Like / dislike are plain form posts (same-origin checked) with a swipe on touch as progressive enhancement; each records a decision-ledger row (kind lean, answer like or dislike).
• [ ] A disliked sibling is closed with a one-line reason the builder sees as a comment; the last liked sibling shows Ship.
• [ ] Tests: like and dislike each write one ledger row; a dislike closes the pull with its reason; a reader without write access gets no buttons and a refused post.
• [ ] A new test file is added to GATE in scripts/gate.ts in the same push (bun test test/check-list.test.ts is green); the last two tries went red on exactly this.
• [ ] If the check goes red on a test this change does not touch, the pull names that test and why it is unrelated; it does not widen the change to fix it.

Files. src/core/decisions.ts, src/web/studio/change.ts, src/web/pages/looks.ts or a new src/web/pages/variants.ts, one new test file.

Moved off P1's umbrella (#587). It needs sibling pulls (#1409), and #1409 is deferred behind the Later gate (#595), so this waits there with it.

Correction: this is back under P1 (#587) and waits on #1571, which replaces #1409.