feat: use ; as artist separator in downloads, add & handling

navidromeArtist() now writes ; instead of / so Navidrome splits
correctly with the updated Tags.Artist.Split config.
Also handles & (e.g. "Artist A & Artist B" → "Artist A;Artist B").

Add fix-artist-separators.sh — one-time Debian script to update
existing library files from " / " to ";" in artist tags.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

fix-artist-separators.sh

@@ -0,0 +1,91 @@
+#!/usr/bin/env bash
+# fix-artist-separators.sh
+# Replaces " / " (space-slash-space) in audio file artist tags with ";"
+#
+# Safe: only matches " / " with surrounding spaces, so Au/Ra and HUNTR/X
+# (no spaces around the slash) are left completely untouched.
+#
+# Requires: ffprobe, ffmpeg, python3
+#
+# Usage:
+#   bash fix-artist-separators.sh [music_dir]           -- dry run (no changes)
+#   bash fix-artist-separators.sh [music_dir] --apply   -- actually modify files
+#
+# Example:
+#   bash fix-artist-separators.sh /opt/navidrome/music --apply
+
+MUSIC_DIR="${1:-/opt/navidrome/music}"
+APPLY=false
+[[ "${2:-}" == "--apply" ]] && APPLY=true
+
+if [[ ! -d "$MUSIC_DIR" ]]; then
+  echo "Error: directory not found: $MUSIC_DIR"
+  exit 1
+fi
+
+if $APPLY; then
+  echo "🔧  APPLY mode — files will be modified"
+else
+  echo "🔍  DRY RUN — no files will be changed (add --apply to apply changes)"
+fi
+echo "📂  Scanning: $MUSIC_DIR"
+echo ""
+
+count_found=0
+count_ok=0
+count_fail=0
+
+get_artist() {
+  ffprobe -v quiet -print_format json -show_format "$1" 2>/dev/null \
+    | python3 -c "
+import sys, json
+data = json.load(sys.stdin)
+tags = data.get('format', {}).get('tags', {})
+print(next((v for k, v in tags.items() if k.lower() == 'artist'), ''))
+" 2>/dev/null
+}
+
+while IFS= read -r -d '' file; do
+  artist=$(get_artist "$file") || continue
+  [[ "$artist" != *" / "* ]] && continue
+
+  new_artist="${artist// \/ /;}"
+  count_found=$((count_found + 1))
+
+  echo "📄  $file"
+  echo "    Before : $artist"
+  echo "    After  : $new_artist"
+
+  if $APPLY; then
+    ext="${file##*.}"
+    tmp="${file%.*}.artist_fix_tmp.$ext"
+    if ffmpeg -i "$file" -map_metadata 0 -metadata "artist=$new_artist" \
+              -c copy "$tmp" -y -loglevel quiet 2>/dev/null; then
+      mv "$tmp" "$file"
+      echo "    ✅ Updated"
+      count_ok=$((count_ok + 1))
+    else
+      rm -f "$tmp"
+      echo "    ❌ Failed"
+      count_fail=$((count_fail + 1))
+    fi
+  fi
+  echo ""
+done < <(find "$MUSIC_DIR" -type f \( \
+  -name "*.mp3" -o -name "*.flac" -o \
+  -name "*.m4a" -o -name "*.ogg"  -o \
+  -name "*.opus" \) -print0)
+
+echo "━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━"
+echo "Files with \" / \" in artist tag: $count_found"
+if $APPLY; then
+  echo "Updated: $count_ok  |  Failed: $count_fail"
+  if [[ $count_ok -gt 0 ]]; then
+    echo ""
+    echo "💡 Trigger a Navidrome rescan to pick up the changes."
+  fi
+else
+  echo ""
+  echo "Run with --apply to fix them:"
+  echo "  bash fix-artist-separators.sh \"$MUSIC_DIR\" --apply"
+fi