deploy: default MPD music_directory to ~/Music

Midgolem was the last fresh rig to set up and the music library lives
in ~/Music/Kolekcja, so ~/HDD/Music — the path inherited from Ignia's
secondary-disk layout — no longer reflects the common case. Three
references flipped: the ASSET_DIRS ensure list, the mpd.conf heredoc,
and the post-install empty-library check + warn message.

scripts/deploy-rig.sh

@@ -220,7 +220,7 @@ fi
 
 ASSET_DIRS=(
   "$HOME/Videos"
-  "$HOME/HDD/Music"
+  "$HOME/Music"
   "$HOME/HDD/Images/Gifs"
   "$HOME/cloud.jakubzych.com/_img/logos"
 )
@@ -372,7 +372,7 @@ write_mpd_conf() {
 # ~/.config/mpd/mpd.conf — generated by scripts/deploy-rig.sh.
 # Re-run the deploy script to regenerate, or hand-edit for local tweaks.
 
-music_directory     "~/HDD/Music"
+music_directory     "~/Music"
 playlist_directory  "~/.config/mpd/playlists"
 db_file             "~/.config/mpd/database"
 state_file          "~/.config/mpd/state"
@@ -421,13 +421,13 @@ else
   fi
 fi
 
-if [[ -d "$HOME/HDD/Music" ]] && [[ -n "$(find "$HOME/HDD/Music" -maxdepth 3 -type f -print -quit 2>/dev/null)" ]]; then
+if [[ -d "$HOME/Music" ]] && [[ -n "$(find "$HOME/Music" -maxdepth 3 -type f -print -quit 2>/dev/null)" ]]; then
   if would "mpc update"; then
     mpc update >/dev/null 2>&1 || warn "mpc update failed (mpd not yet running?)"
     ok "MPD library scan kicked off"
   fi
 else
-  warn "~/HDD/Music is empty — MPD will have no tracks until you populate it"
+  warn "~/Music is empty — MPD will have no tracks until you populate it"
 fi
 
 # Avahi for zeroconf advertisement (system service).