docs: add projects feature documentation and finalize integration
- Add comprehensive projects feature documentation (docs/projects-feature.md)
- Add testing guide and checklist (test_projects_feature.js)
- Update .gitignore to exclude database files
- Include Task 13 completion summary
Documentation covers:
- Feature overview and key capabilities
- Project creation (manual and smart suggestions)
- Session assignment (automatic and manual)
- Project management (edit, delete, restore)
- Complete API reference
- Smart suggestions explanation
- Troubleshooting and FAQ
Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>
