Fix odysseus-calendar list dropping in-progress / multi-day events (#2065)

cmd_list filtered on the event START falling inside the window
(dtstart >= start AND dtstart < end). The canonical web route
(routes/calendar_routes.py) and the recurrence contract test use
OVERLAP semantics for non-recurring events: dtstart < end AND
dtend > start. So an event that began before the window but is still
ongoing inside it — e.g. a 09:00-17:00 conference listed at 14:00, or
any multi-day event spanning the window — was silently dropped by the
CLI even though the web UI shows it. Use overlap, matching the route.
dtend is NOT NULL in the schema, so no null-end regression.

scripts/odysseus-calendar

@@ -103,9 +103,13 @@ def cmd_list(args) -> None:
     end = _parse_dt(args.end) if args.end else (start + timedelta(days=30))
     db = SessionLocal()
     try:
+        # Overlap semantics, matching the web route (routes/calendar_routes.py)
+        # and the recurring-expansion contract: an event is in the window when
+        # it starts before the window end AND ends after the window start. This
+        # includes multi-day / in-progress events that began before `start`.
         q = db.query(CalendarEvent).filter(
-            CalendarEvent.dtstart >= start,
             CalendarEvent.dtstart < end,
+            CalendarEvent.dtend > start,
         )
         if args.calendar:
             cal = db.query(CalendarCal).filter(CalendarCal.name == args.calendar).first()