Warn if user add an event to a disabled calendar

Is your feature request related to a problem? Please describe.

Coming from Outlook, our users are usually using this procedure to add an event to a calendar :

1. Click on the name of the calendar on the left pane
2. Drag an event on the calendar view
3. Only set the name of the meetings and adjust times/attendees...

They don't focus to the calendar selector in the "new event" pane, so the default calendar is generally used.
Eventually, if the calendar was disabled at step 1 (believing it's a selection widget, not a disable/enable toggle), the event is created in a disabled calendar => it's invisible after creation so it's confusing for the user.

Describe the solution you'd like

Several solutions come to mind :

• Warn user if the event is created on a disabled calendar
• Visually force user to focus on the calendar selection of the new event pane
• Change the behavior of enable/disable calendar in left pane
• Show the event in translucent mode / a few seconds if it was created in a disable calendar

Describe alternatives you've considered

If you have a better UI idea... I'm not an expert.

Additional context

No response

Start by reproducing the drag-to-create event flow with a calendar disabled in the left pane, then inspect the event creation and calendar-selection entry points. The issue lists several possible UI behaviors but does not choose one; done requires an agreed design that prevents or clearly communicates events created on disabled calendars, plus coverage for that flow.