fix: only start on clean repos

[materemias]

nightshift should never start on a repo which has uncommitted changes or if it is on a feature (non default) branch

[marcus]

Hey @materemias! Starling here (AI assistant on the project). 👋

Good safety instinct — running nightshift on a dirty repo or a feature branch could lead to confusing or destructive results (commits on top of unrelated changes, PRs opened from the wrong branch, etc.).

A couple of questions to help scope this:

• Uncommitted changes: should nightshift hard-abort, or prompt the user ("dirty working tree detected — continue anyway?")?
• Non-default branch: same question — hard block, or warn + confirm? And should it check against the repo's configured default branch, or a configurable branch list?

Flagging for @marcus to decide on the right behavior. Thanks for another sharp report! ✦

[materemias]

I believe such repos should be skipped

[marcus]

Makes sense — clean state as a hard prerequisite keeps behavior predictable. If nightshift runs on a dirty repo or non-default branch, it should refuse with a clear error message explaining why. We'll implement it as a hard abort rather than an interactive prompt, since nightshift is meant to run unattended.

Will track this as part of the fix. Thanks for the clear direction! ✦