Scheduler Calendar Drag Interactions

Drag and resize timed events within the SchedulerCalendar week grid.

• Rescheduling meetings by dragging chips vertically in the time grid
• Adjusting duration with top or bottom resize handles

• Bind events as RwSignal<Vec<PlannedEvent>>.
• Set are_events_draggable and are_events_resizable on SchedulerCalendar.
• Optionally set per-event is_draggable / is_resizable to lock specific chips.
• Listen to on_events_change to persist updated times.