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.

duty_teller/run.py

@@ -11,6 +11,14 @@ from telegram.ext import ApplicationBuilder
 from duty_teller import config
 from duty_teller.config import require_bot_token
 from duty_teller.handlers import group_duty_pin, register_handlers
+
+
+async def _resolve_bot_username(application) -> None:
+    """If BOT_USERNAME is not set from env, resolve it via get_me()."""
+    if not config.BOT_USERNAME:
+        me = await application.bot.get_me()
+        config.BOT_USERNAME = (me.username or "").lower()
+        logger.info("Resolved BOT_USERNAME from API: %s", config.BOT_USERNAME)
 from duty_teller.utils.http_client import safe_urlopen
 
 logging.basicConfig(
@@ -69,6 +77,7 @@ def main() -> None:
         ApplicationBuilder()
         .token(config.BOT_TOKEN)
         .post_init(group_duty_pin.restore_group_pin_jobs)
+        .post_init(_resolve_bot_username)
         .build()
     )
     register_handlers(app)