The sound picker's preview always played the default beep, even for the other choices, on a subpath deployment.
playFile() used a raw '/notification/x.mp3' path, which 404s under a deployment base path (e.g. /webmail); audio.play() then rejected and fell back to the beep for every non-default choice. Prefix the file with withBasePath().
The default beep was a 150 ms tone with no envelope - easy to miss on Bluetooth outputs, whose audio path can take 100-200 ms to wake up and route. Lengthen it to ~0.45 s with a fade in/out (also removes click artifacts).
Add client-side calendar event notification system that evaluates JMAP
CalendarEventAlert triggers and displays toast notifications when alert
times are reached. Includes configurable notification sound, acknowledged
alert persistence, and proactive event fetching for background alerts.
Also mounts ToastContainer globally to fix silent toast failures.
