Add genre normalization: German/variant genres → canonical Jellyfin names

_GENRE_MAP translates common German genre names (Volksmusik, Schlager,
Marschmusik, Klassik …) and English variants (rhythm and blues, swing music …)
to consistent Jellyfin-friendly labels. All-upper or all-lower genres without
a mapping entry are title-cased. Applied in resolve() before building AlbumProposal.

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

metadata_resolver.py

@@ -33,6 +33,63 @@ try:
 except ImportError:
     HAS_ANTHROPIC = False
 
+# ---------------------------------------------------------------------------
+# Genre normalization
+# ---------------------------------------------------------------------------
+
+_GENRE_MAP: Dict[str, str] = {
+    # Deutsch → Englisch (Jellyfin-Standardbegriffe)
+    "volksmusik": "Folk",
+    "volkslieder": "Folk",
+    "volkslied": "Folk",
+    "heimatlieder": "Folk",
+    "schlager": "Schlager",
+    "deutsche schlager": "Schlager",
+    "marsch": "March",
+    "marschmusik": "March",
+    "militaermusik": "March",
+    "militärmusik": "March",
+    "kirchenmusik": "Sacred",
+    "chormusik": "Choral",
+    "kinderlieder": "Children",
+    "weihnachtslieder": "Christmas",
+    "weihnachtsmusik": "Christmas",
+    "blasmusik": "Brass Band",
+    "operette": "Operetta",
+    "oper": "Opera",
+    "kammermusik": "Chamber Music",
+    "klassik": "Classical",
+    "classic": "Classical",
+    "klassische musik": "Classical",
+    "barock": "Baroque",
+    "romantik": "Romantic",
+    # Englische Varianten vereinheitlichen
+    "rhythm and blues": "R&B",
+    "rhythmic soul": "R&B",
+    "rock and roll": "Rock 'n' Roll",
+    "rock & roll": "Rock 'n' Roll",
+    "easy listening": "Easy Listening",
+    "vocal pop": "Pop",
+    "adult contemporary": "Pop",
+    "big band": "Big Band",
+    "swing music": "Swing",
+    "latin jazz": "Latin Jazz",
+    "bossa nova": "Bossa Nova",
+    "nueva cancion": "Nueva Canción",
+}
+
+
+def normalize_genre(genre: Optional[str]) -> Optional[str]:
+    if not genre:
+        return genre
+    key = genre.strip().lower()
+    normalized = _GENRE_MAP.get(key)
+    if normalized:
+        return normalized
+    # Titlcase wenn nicht in der Map (verhindert ALL CAPS oder all lowercase)
+    return genre.strip().title() if genre == genre.upper() or genre == genre.lower() else genre.strip()
+
+
 _MB_RATE_LIMIT = 1.1   # seconds between MusicBrainz requests
 _last_mb_call = 0.0
 ACOUSTID_API_KEY  = os.getenv("ACOUSTID_API_KEY", "")
@@ -505,7 +562,7 @@ def resolve(
         album=album,
         albumartist=albumartist,
         date=year,
-        genre=genre,
+        genre=normalize_genre(genre),
         label=label,
         mbid=release_mbid,
         cover_path=None,