🌟Allow messages to target attendees who opted in for marketing #1303

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

Currently, when sending messages to attendees, there is no way to easily filter and select only attendees who have opted in for marketing.

Describe the solution you'd like

Allow organisers to select attendees based on their marketing consent status when sending messages.

Additional context

This would make it easier to send marketing communications while respecting attendee preferences.