Per-number notification settings

We run several WhatsApp numbers in one workspace and each team member only handles one or two of them. Right now notifications are workspace-wide, so everyone gets alerted for every number, or nobody gets alerted at all.

Request: let each user choose which numbers trigger sound/push notifications in their own notification settings (a simple checklist of the org's numbers). Ideally combined with the existing notification-type toggles, so I can say "sound for new messages on number A and B, silent for the rest".

This is the biggest source of notification noise for multi-number teams, and it's a per-user preference, so it shouldn't affect how the workspace is configured for others.