feat: add team calendar ICS endpoint and related functionality

- Implemented a new API endpoint to generate an ICS calendar for team duty shifts, accessible via a valid token.
- Enhanced the `calendar_link` command to return both personal and team calendar URLs.
- Added a new function to build the team ICS file, ensuring each event includes the duty holder's name in the description.
- Updated tests to cover the new team calendar functionality, including validation for token formats and response content.
- Revised internationalization messages to reflect the new team calendar links.

duty_teller/api/app.py

@@ -17,8 +17,12 @@ from duty_teller.api.dependencies import (
     get_validated_dates,
     require_miniapp_username,
 )
-from duty_teller.api.personal_calendar_ics import build_personal_ics
-from duty_teller.db.repository import get_duties_for_user, get_user_by_calendar_token
+from duty_teller.api.personal_calendar_ics import build_personal_ics, build_team_ics
+from duty_teller.db.repository import (
+    get_duties,
+    get_duties_for_user,
+    get_user_by_calendar_token,
+)
 from duty_teller.db.schemas import CalendarEvent, DutyWithUser
 
 log = logging.getLogger(__name__)
@@ -94,6 +98,38 @@ def list_calendar_events(
     return [CalendarEvent(date=e["date"], summary=e["summary"]) for e in events]
 
 
+@app.get(
+    "/api/calendar/ical/team/{token}.ics",
+    summary="Team calendar ICS",
+    description=(
+        "Returns an ICS calendar with all team duty shifts. Each event has "
+        "DESCRIPTION set to the duty holder's name. No Telegram auth; access by token."
+    ),
+)
+def get_team_calendar_ical(
+    token: str,
+    session: Session = Depends(get_db_session),
+) -> Response:
+    """Return ICS calendar with all duties (event_type duty only). Token validates user."""
+    if not _is_valid_calendar_token(token):
+        return Response(status_code=404, content="Not found")
+    user = get_user_by_calendar_token(session, token)
+    if user is None:
+        return Response(status_code=404, content="Not found")
+    today = date.today()
+    from_date = (today - timedelta(days=365)).strftime("%Y-%m-%d")
+    to_date = (today + timedelta(days=365 * 2)).strftime("%Y-%m-%d")
+    all_duties = get_duties(session, from_date=from_date, to_date=to_date)
+    duties_duty_only = [
+        (d, name) for d, name in all_duties if (d.event_type or "duty") == "duty"
+    ]
+    ics_bytes = build_team_ics(duties_duty_only)
+    return Response(
+        content=ics_bytes,
+        media_type="text/calendar; charset=utf-8",
+    )
+
+
 @app.get(
     "/api/calendar/ical/{token}.ics",
     summary="Personal calendar ICS",