- Sync imported progress (completed, scored, done, reset) to composite progress model and recompute composite_percent
- Prevent caching of /progress-report.json with Cache-Control: no-store and frontend cache-busting timestamp
- Provide inline expected format guides in exported CSV lesson headers (e.g. [completed], [<earned>/<total>], [done:<1|0>:<earned>/N])
- Support robust slug extraction from formatted headers in CSV roundtrip import with full backward compatibility
- Add example composite lesson (exercise + quiz) in examples/content/dasar/composite_test.md
- Add comprehensive unit and integration tests covering progress synchronization, header formatting, and roundtrip workflows
