Onboarding music for Soothia's welcome page (onboarding.mp3).

Title:   Medieval Music – Cobblestone Village
Artist:  not recorded (operator-supplied file)
Source:  not provided yet (the brief's "Music license / source" line was left as its placeholder twice)
License: not provided yet

The file was re-encoded from the original (stereo MP3, 128 kbps, 4:18) to
mono MP3 at 56 kbps so it stays under 2 MB inside the extension. It plays
only on welcome.html, never on websites.
