Standardizes the phased development workflow:
- /backend-phase status - Show current phase and progress
- /backend-phase next - Show details of next task
- /backend-phase start <id> - Begin working on task
- /backend-phase done <id> - Mark task complete with tests
- /backend-phase plan - Create plan for next NOT_STARTED phase
Reads from PROJECT_PLAN_MASTER.json and project_plans/PHASE_*.json.
Ensures dependencies are met before starting tasks and tests exist
before marking complete.
Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>