New: UnifiedPush support. With a UnifiedPush app installed (ntfy, NextPush), JMAP accounts receive new mail through it, so Sterna keeps no connection open and shows no permanent notification. Without one, nothing changes.

New: watch folders beyond the Inbox. Turn on "Notify about new mail" for any folder (Sieve-filtered folders included) from its menu in the drawer.

New: a single "New mail delivery: Instant / Battery saver" setting, and a per-account line showing how push is delivered.
