A test pins MCP `variant`: like or dislike only, a later vote replaces the earlier, and a dislike closes the pull with its reason #7166

src/http/mcp/tools/variant.ts refuses invalid_answer, and no test names it. Each case calls the tool through /mcp with a real token, as test/mcp.test.ts does.

Done:

• [ ] A new test: on a pull with sibling variants, like then dislike leaves one vote, the dislike. The pull is closed with the given reason as its one comment.
• [ ] answer: "meh" is invalid_answer, and no vote is stored.
• [ ] A pull that is not a variant, or one the caller cannot read, is refused, and nothing changes.

Files: test/mcp-variant.test.ts

If the test finds the behaviour wrong, fix the module it names in the same pull and say so. If the check fails in a test this pull does not touch, name it in the pull rather than widening the change.

Before pushing: bun x tsc --noEmit and the new test.