A test pins setting how a fork follows its parent: an admin and writer only, a known mode only #7093

setFollowMode in src/actions/follow.ts refuses with not_following, forbidden and invalid_mode, and no test names any of them.

Done:

• [ ] A new test: the fork's admin sets each mode isFollowMode accepts, and reading it back gives that mode.
• [ ] An unknown mode is invalid_mode. A repository that follows no parent is not_following. A reader is forbidden.
• [ ] After each refusal, the mode is unchanged.

Files: test/follow-mode-refusals.test.ts

If the test finds the behaviour wrong, fix the action 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.