Music player in the sound settings: pick any calm track or automatic

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

lang/en.lang

@@ -1115,6 +1115,8 @@ ov.summary = {0} creatures - wages {1} gold per payday - mood {2}%
 ov.none = No creatures yet. Build a lair and a mushroom garden and claim a portal.
 ov.hint = Lv, mood, wage, job, health - click: go there
 set.voice = Crookfinger's voice
+set.track = Music track
+val.track_auto = Automatic
 
 # ---- campaign editor, block scripts, demo campaign
 menu.back_editor = Back to the editor