Notification queue cap (MaxNotifications)

[corradedied]

Firing many notifications fast caused unbounded screen clutter with no way to remove old ones — Library.Notifications is an unordered dictionary, so "oldest" was unknowable.

What changed

• Library.NotificationQueue — ordered array parallel to the existing dict, so oldest is always [1]
• Library.MaxNotifications (default 10) — on each Notify insert, removes from the front of the queue until under cap. 0 = unlimited. Persist notifications are exempt and will remain untouched.
• Data:Destroy() — removes the entry from the queue on natural expiry so dead references don't block future evictions
• Templates.Window + CreateWindow — wires the setting into the window config so it can be set at the call site:

Library:CreateWindow({ MaxNotifications = 5 })

Unload path clears NotificationQueue alongside Notifications.