A test pins the terminal's history: the log pages through a real "load more" row, and a commit opens its diff #6982

src/tui/screens/commits.ts pages the log with --skip and keeps "load more" as a real row. No test opens it.

Done:

• [ ] A new test makes a repository with more commits than one page. The first page lists them newest first. The cursor can land on "load more", and choosing it appends the next page with no commit twice and none missing.
• [ ] Choosing a commit shows its message and its diff.
• [ ] A branch other than the default shows its own log.

Files: test/tui-commits.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.