Fix music file matching: Mvt3 was resolving to Mvt1 for every season

The old pattern *Mvt*3* matched .mp3 in every MP3 filename, so sort|head-1
always picked track 01 (Mvt1). Fix by finding all files for the season
then filtering with grep -iE "Mvt[^0-9]*N[^0-9]", which requires the
movement number to be surrounded by non-digit characters (space, dot,
underscore) and cannot match digits embedded in .mp3 or track prefixes.

https://claude.ai/code/session_01C4jbd3waXG3eKZYbGUjLUQ

4-seasons.sh

@@ -36,7 +36,8 @@ eval "$_season_info"
 echo "Season=$SEASON  Mvt=$MVT_NUM  Year=$ASTRO_YEAR  Day=$DAY_OF_MVT/$DAYS_IN_MVT  LastDay=$IS_LAST_DAY"
 
 # ── Locate music file and get its duration ────────────────────────────────────
-music_file=$(find "$music_base_dir" -type f -iname "*${SEASON}*Mvt*${MVT_NUM}*" | sort | head -n 1)
+music_file=$(find "$music_base_dir" -type f -iname "*${SEASON}*" \
+    | grep -iE "Mvt[^0-9]*${MVT_NUM}[^0-9]" | sort | head -n 1)
 if [ -z "$music_file" ] || [ ! -f "$music_file" ]; then
     echo "ERROR: Music file not found for $SEASON Mvt $MVT_NUM in $music_base_dir"
     exit 1