* feat(settings): move utility agents to main agents page
- Extract utility agents section into reusable component
- Add utility agents section to main agents settings page
- Remove separate utility agents page and sidebar link
- Consolidate all agent-related settings in one location
* style: format utility-agents-section.tsx with prettier
* fix: add error handling for utility agents operations
- Add try/catch with rollback for handleDefaultChange
- Add try/catch for onDelete to prevent UI inconsistency on failure
Addresses CodeRabbit review comments.
Carlos Florêncio