kit v0.10.0: split apply output by auto-merge eligibility

Breaking change to apply-result.json contract:
- New: auto_merge_group and review_group (optional ApplyGroup objects)
- Removed: flat applied array, single auto_merge_eligible boolean

Each group has its own branch_hint, commit_message, mr_title, mr_body.
The CI pipeline component creates separate MRs per group so low-tier
patches auto-merge without being blocked by own/high tier tools.

AppliedUpdate now carries eval_reason and review_reasons for
richer MR descriptions on review-needed updates.