feat: add calendar subscription token functionality and ICS generation

- Introduced a new database model for calendar subscription tokens, allowing users to generate unique tokens for accessing their personal calendar.
- Implemented API endpoint to return ICS files containing only the subscribing user's duties, enhancing user experience with personalized calendar access.
- Added utility functions for generating ICS files from user duties, ensuring proper formatting and timezone handling.
- Updated command handlers to support the new calendar link feature, providing users with easy access to their personal calendar subscriptions.
- Included unit tests for the new functionality, ensuring reliability and correctness of token generation and ICS file creation.

duty_teller.egg-info/SOURCES.txt

@@ -13,6 +13,7 @@ duty_teller/api/__init__.py
 duty_teller/api/app.py
 duty_teller/api/calendar_ics.py
 duty_teller/api/dependencies.py
+duty_teller/api/personal_calendar_ics.py
 duty_teller/api/telegram_auth.py
 duty_teller/db/__init__.py
 duty_teller/db/models.py
@@ -37,10 +38,12 @@ duty_teller/utils/dates.py
 duty_teller/utils/handover.py
 duty_teller/utils/user.py
 tests/test_app.py
+tests/test_calendar_token_repository.py
 tests/test_config.py
 tests/test_duty_schedule_parser.py
 tests/test_i18n.py
 tests/test_import_duty_schedule_integration.py
+tests/test_personal_calendar_ics.py
 tests/test_repository_duty_range.py
 tests/test_telegram_auth.py
 tests/test_utils.py