feat: organized album directory and persistent /music bind-mount

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

worker/lyra_worker/library.py

@@ -0,0 +1,19 @@
+import re
+
+from lyra_worker.types import MBTarget
+
+_ILLEGAL = re.compile(r'[<>:"/\\|?*\x00-\x1f]')
+
+
+def safe_name(s: str) -> str:
+    """A filesystem-safe path component (single segment, no separators)."""
+    cleaned = _ILLEGAL.sub("_", s).strip().strip(".").strip()
+    return cleaned or "Unknown"
+
+
+def album_dir(dest_root: str, target: MBTarget) -> str:
+    """`{dest_root}/{safe artist}/{safe album}[ (year)]`."""
+    album = safe_name(target.album)
+    if target.year:
+        album = f"{album} ({target.year})"
+    return f"{dest_root}/{safe_name(target.artist)}/{album}"