#54 Notification sound toggle + do-not-disturb schedule

[Anonymous]

Originally created by: kristofferR

Notifications are all-or-nothing (mute all / hide preview). Add:

• notification sound on/off
• a do-not-disturb schedule (suppress delivery between a start and end time)

Wired through the existing `carrier:notify` bridge.

[Anonymous]

Ticket changed by: kristofferR

• status: open --> closed

[Anonymous]

Originally posted by: kristofferR

Done in [#64]: notification-sound toggle (also gives Windows toasts sound — they were always silent before) and a DND window with overnight-wrap support; DND suppresses delivery while the badge keeps updating.