- Introduced a new function `get_authenticated_username` to centralize Mini App authentication logic, improving code readability and maintainability.
- Updated the duty fetching logic to map unknown event types to "duty" for consistent API responses.
- Enhanced the `get_duties` function to include duties starting on the last day of the specified date range.
- Improved session management in the database layer to ensure rollback on exceptions.
- Added tests to validate the new authentication flow and event type handling.
- Added support for fetching and parsing external ICS calendars, allowing events to be displayed on the duty grid.
- Introduced a new API endpoint `/api/calendar-events` to retrieve calendar events within a specified date range.
- Updated configuration to include `EXTERNAL_CALENDAR_ICS_URL` for specifying the ICS calendar URL.
- Enhanced the web application to visually indicate days with events and provide event summaries on hover.
- Improved documentation in the README to include details about the new calendar integration and configuration options.
- Updated tests to cover the new calendar functionality and ensure proper integration.
- Added `__all__` declaration in `db/__init__.py` for better module export management.
- Simplified command text formatting in `handlers/commands.py` for improved readability.
- Refactored error handler function signature in `handlers/errors.py` for better code style.
- Introduced comprehensive tests for API duties and Telegram authentication in new test files.
