chore: remove unused imports in calendar_routes (#2221)

routes/calendar_routes.py imports several names it never uses (pyflakes):
typing.Tuple, dateutil.rrule.{rruleset,DAILY,WEEKLY,MONTHLY,YEARLY}, and
auth_helpers.get_current_user. Drop them (the whole DAILY/WEEKLY/MONTHLY/
YEARLY line goes; rrulestr and require_user are kept). No behaviour change.

routes/calendar_routes.py

@@ -3,16 +3,15 @@
 import logging
 import uuid
 from datetime import datetime, date, timedelta
-from typing import Optional, List, Tuple
+from typing import Optional, List
 
 from fastapi import APIRouter, HTTPException, Request, UploadFile, File
 from pydantic import BaseModel
 from sqlalchemy import or_, and_
-from dateutil.rrule import rrulestr, rruleset
-from dateutil.rrule import DAILY, WEEKLY, MONTHLY, YEARLY
+from dateutil.rrule import rrulestr
 
 from core.database import SessionLocal, CalendarCal, CalendarEvent
-from src.auth_helpers import get_current_user, require_user
+from src.auth_helpers import require_user
 from src.upload_limits import read_upload_limited
 
 logger = logging.getLogger(__name__)