Initial implementation of Music Metadata Enricher

AI-powered per-album pipeline: scan → local hints → MusicBrainz/Discogs/Claude
resolve → cover art → interactive or auto review → tag write + rename + report.
All external dependencies optional; 17/17 unit tests passing.

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

scanner.py

@@ -0,0 +1,59 @@
+from __future__ import annotations
+
+import sys
+from pathlib import Path
+from typing import List
+
+from models import AlbumScan, AUDIO_EXTENSIONS, IMAGE_EXTENSIONS, TRACKLIST_EXTENSIONS
+
+
+def _is_hidden(name: str) -> bool:
+    return name.startswith(".") or name.startswith("_")
+
+
+def scan_album(album_dir: Path) -> AlbumScan:
+    result = AlbumScan(album_dir=album_dir)
+
+    for dirpath, dirnames, filenames in album_dir.walk() if hasattr(album_dir, "walk") else _os_walk(album_dir):
+        dirnames[:] = [d for d in dirnames if not _is_hidden(d)]
+        current = Path(dirpath) if isinstance(dirpath, str) else dirpath
+
+        for name in filenames:
+            if _is_hidden(name):
+                continue
+            p = current / name
+            ext = p.suffix.lower()
+
+            if ext in AUDIO_EXTENSIONS:
+                result.audio_files.append(p)
+            elif ext in IMAGE_EXTENSIONS:
+                result.image_files.append(p)
+            elif ext in TRACKLIST_EXTENSIONS:
+                result.tracklist_files.append(p)
+            else:
+                result.other_files.append(p)
+
+    result.audio_files.sort()
+    result.image_files.sort()
+    result.tracklist_files.sort()
+    return result
+
+
+def _os_walk(album_dir: Path):
+    import os
+    return os.walk(
+        album_dir,
+        followlinks=False,
+        onerror=lambda e: print(f"⚠️ Scan-Fehler: {e}", file=sys.stderr),
+    )
+
+
+def collect_album_dirs(root: Path) -> List[Path]:
+    dirs: List[Path] = []
+    try:
+        for item in sorted(root.iterdir()):
+            if item.is_dir() and not _is_hidden(item.name):
+                dirs.append(item)
+    except (PermissionError, OSError) as e:
+        print(f"⚠️ Lesefehler {root}: {e}", file=sys.stderr)
+    return dirs