The idle notification scheduler was initialized with platform 'unsupported'
before platform detection had run. This stale value was passed to send/playSound
callbacks, causing sendSessionNotification to silently no-op (no switch case for
'unsupported'). Session-idle notifications never fired as a result.
Fix: remove platform from scheduler options entirely. Callbacks now resolve
platform via ensureNotificationPlatform() which is sync, cached, and already
called by each event handler before scheduling.
mrosnerr