- fix(api): heartbeat endpoint no longer requires request body, fix spa_fallback
404 handler causing 500 on API routes, add db.refresh() in agent update/heartbeat
- feat(time): unify all frontend time display to Beijing time (Asia/Shanghai)
via new beijing() utility; backend alert messages also use BJT
- feat(ui): collapse AI agent instruction panel on Tasks page by default
- chore: add backend/app/utils.py and frontend/src/utils/time.js
