Major changes:
- Plan-first workflow: AI generates structured plan before code, with
plan review card (Modify Plan / Start Coding / Skip to Code)
- Post-coding UX: Preview + Request Modifications buttons after code gen
- OpenRouter integration: 4th AI provider with 20+ model support
- Enhanced prompt engine: 9 strategies, 11+ intent patterns, modular
- PLAN MODE system prompt block in all 4 services
- Fixed stale React closure in approveAndGenerate with isApproval flag
- Fixed canvas auto-opening during plan phase with wasIdle gate
- Updated README, CHANGELOG, .env.example, version bump to 1.3.0
