feat(skills): add alternatives exploration and self-review checklist to writing-plans #838
Description
Purpose
Strengthen writing-plans skill to require ≥2 alternative approaches per decision and a self-review checklist before plan submission.
Changes
packages/rules/.ai-rules/skills/writing-plans/SKILL.md— Add Alternatives section template + Self-Review Gate checklist
Acceptance Criteria
- Each non-trivial decision requires ≥2 approaches with trade-off analysis
- Self-review checklist added (paths verified, steps bite-sized, risks identified, TDD applied)
- Plan template updated with new sections
- Can be merged independently