Improvements and fixes

The "Tickets" page now lists only tickets that are not closed. A member whose role changes now receives a notification of their own.

• The "Tickets" page now lists only tickets that are not closed, unless the status filter or "Show closed tickets" on an empty list is used.
• A member whose role in the organization is changed now receives a notification of their own, naming the new role.
• Notifications about a ticket now name its new status, and a mentioned person by name rather than by account.
• Notifications delivered outside the app now go out promptly after the web app is closed or signed out, instead of up to 45 seconds later.