[NOT FULLY WORKING] Added frontend react native interface.

backend/modules/calendar/api.py

@@ -25,6 +25,8 @@ def get_events(
     start: datetime | None = None,
     end: datetime | None = None
 ):
+    start = None if start == "" else start
+    end = None if end == "" else end
     return get_calendar_events(db, user.id, start, end)
 
 @router.put("/events/{event_id}", response_model=CalendarEventResponse)