kit-registry v3.0.0: split MRs by auto-merge eligibility

Breaking change: reads apply-result.json with two optional groups
(auto_merge_group, review_group) instead of a flat applied array.

- Creates separate branch + MR per group
- Auto-merge group gets glab mr merge --auto
- Review group stays open for human review
- Pipeline restructured: sense → evaluate → apply-toml → commit-and-mr
- Dotenv signaling for conditional execution between stages
- Groups process independently (first failure does not block second)
- File staging verified with expected vs actual count