Add MusicBrainz barcode lookup (scan --barcode and interactive rip)

- New module musicbrainz.py: lookup_by_barcode() via EAN-13/UPC-12,
  two-step API (barcode search → release detail with recordings),
  respects 1 req/s rate limit with User-Agent header
- cli.py: scan command gets --barcode option as highest-priority mode
  (no images needed); _scan_to_album() dispatches to MusicBrainz first
- ripper.py: interactive_rip() prompts for optional EAN after album name;
  MusicBrainz data (incl. year) takes priority over CDDB for album.json;
  album_root.mkdir() added so JSON can be written even when MB changes dir
- tests: test_musicbrainz.py (16 tests), test_ripper.py +6 barcode tests

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

src/musiksammlung/ripper.py

@@ -14,6 +14,7 @@ from musiksammlung.config import AudioFormat
 from musiksammlung.models import Album as AlbumModel
 from musiksammlung.models import Disc as DiscModel
 from musiksammlung.models import Track as TrackModel
+from musiksammlung.musicbrainz import lookup_by_barcode
 
 logger = logging.getLogger(__name__)
 
@@ -435,6 +436,26 @@ def interactive_rip(config: RipperConfig) -> None:
         if not album_name:
             album_name = f"Album{album_counter}"
 
+        # Optional: EAN/Barcode für MusicBrainz-Lookup
+        raw_ean = input("EAN/Barcode für MusicBrainz (Enter = überspringen): ")
+        ean = _clean_input(raw_ean)
+        mb_album: AlbumModel | None = None
+        if ean:
+            try:
+                print(f"  MusicBrainz-Suche nach Barcode {ean} ...", flush=True)
+                mb_album = lookup_by_barcode(ean)
+                print(
+                    f"  ✓ {mb_album.artist} – {mb_album.album}"
+                    f" ({mb_album.year or '?'},"
+                    f" {sum(len(d.tracks) for d in mb_album.discs)} Tracks)",
+                    flush=True,
+                )
+                # Albumnamen aus MusicBrainz übernehmen, wenn nicht manuell gesetzt
+                if album_name == f"Album{album_counter}":
+                    album_name = mb_album.album or album_name
+            except Exception as e:
+                print(f"  MusicBrainz: kein Treffer — {e}", flush=True)
+
         disc_counter = 1
         all_discs: list[DiscModel] = []
 
@@ -498,10 +519,20 @@ def interactive_rip(config: RipperConfig) -> None:
 
             disc_counter += 1
 
-        if all_discs:
+        if mb_album:
+            # MusicBrainz-Daten haben Priorität (inkl. Jahr, kuratierte Titel)
+            album_model = mb_album
+            album_root = config.output_dir / _sanitize_name(mb_album.album or album_name)
+        elif all_discs:
             artist = all_discs[0].tracks[0].artist or album_name
             album_model = AlbumModel(artist=artist, album=album_name, discs=all_discs)
             album_root = config.output_dir / _sanitize_name(album_name)
+        else:
+            album_root = config.output_dir / _sanitize_name(album_name)
+            album_model = None
+
+        if album_model is not None:
+            album_root.mkdir(parents=True, exist_ok=True)
             json_path = album_root / "album.json"
             json_path.write_text(
                 album_model.model_dump_json(indent=2), encoding="utf-8"