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.
