Keep repository kickoff and cleanup reachable under the write guard

A repository guard must leave a compliant path to satisfy its own kickoff preconditions. If kickoff requires a clean checkout but the guard blocks git stash before kickoff, the workflow deadlocks. Allow narrowly scoped reversible cleanup before activation, or let kickoff safely operate on a designated clean worktree while validating that worktree's issue, branch, and PR. This applies to helper-driven repository guards; it does not justify bypassing a failed guard or deleting unrelated work.

Applies when: A repository policy requires clean state before issue kickoff and intercepts all Git writes. Keywords: repository hook Linear kickoff dirty checkout stash clean worktree deadlock