[Feature]: Stabilize the core app before adding new features

## Summary\n\nBefore adding new features, it would be fundamental to make the app fully functional and resolve existing core stability/usability problems.\n\n## Problems to address first\n\n- **Mobile responsiveness:** the UI should work reliably on mobile devices.\n- **Agent interaction:** interactions between agents need to be predictable, stable, and easy to understand.\n- **Interrupted cron tasks:** scheduled/cron tasks should not be left in broken or inconsistent states.\n- **Session organization:** sessions should be organized clearly and consistently.\n\n## Suggested priority\n\n1. Audit and fix mobile/responsive UI regressions.\n2. Review and document agent-to-agent interaction flows.\n3. Harden cron/scheduled task handling, including interruption, retry, and recovery behavior.\n4. Improve session organization and navigation.\n5. Only after these are stable, continue adding new features.\n\n## Expected outcome\n\nA stable, usable baseline that prevents new features from compounding existing product and reliability issues.