- Added new endpoints for listing calendars, events, creating/updating/deleting events, and handling free/busy requests.
- Implemented ETag/If-Match support for event updates to ensure data integrity.
- Introduced functionality for responding to invitations and creating Meet links from events.
- Enhanced validation for event creation and updates, including attendee email checks.
- Updated README documentation to reflect the new Calendar API features and usage examples.
- Revised project checklist to indicate completion of Calendar API enhancements.