feat: enhance duty information handling with contact details and current duty view

- Added `bot_username` to settings for dynamic retrieval of the bot's username.
- Implemented `_resolve_bot_username` function to fetch the bot's username if not set, improving user experience in group chats.
- Updated `DutyWithUser` schema to include optional `phone` and `username` fields for enhanced duty information.
- Enhanced API responses to include contact details for users, ensuring better communication.
- Introduced a new current duty view in the web app, displaying active duty information along with contact options.
- Updated CSS styles for better presentation of contact information in duty cards.
- Added unit tests to verify the inclusion of contact details in API responses and the functionality of the current duty view.

tests/test_import_duty_schedule_integration.py

@@ -77,7 +77,7 @@ def test_import_creates_users_and_duties(db_url):
     assert "2026-02-16T06:00:00Z" in starts
     assert "2026-02-17T06:00:00Z" in starts
     assert "2026-02-18T06:00:00Z" in starts
-    for d, _ in duties:
+    for d, *_ in duties:
         assert d.event_type == "duty"