Address review on the review trust gate
Commit

- A missing user.email now gates even an empty range.
- Gate flags are validated before any mode runs (--list --json fails).
- Inspection is bounded: config files over 1 MiB are unknown, a directory lists at most 100 items, and over 20000 config tree entries fails closed.
- A failed pinned checkout removes its worktree even if the context was cancelled.
- The --trust-target error names both SHA lengths, and the default branch resolves through go-git.
Co-Authored-By: Claude Opus 5.5 noreply@anthropic.com Entire-Checkpoint: 01M47FSA4TJ3MVWJCC5WFPDEAZ
Checkpoints
Checkpoint 1