Backfill album release_date from stream tags when T2Tunes metadata omits it

T2Tunes albumList entries may not include a release_date field, leaving the
$year path template empty. get_album() now falls back to the first track's
release_date (populated from the FLAC date tag via get_album_tracks) when
album metadata has none. Also try camelCase releaseDate key at all albumList
read sites (Album.from_metadata, get_album, _fetch_album_metas consumers).

1 new test: release_date backfilled from stream date tag when absent from
album metadata. date tag "2024-11-22" added to MEDIA_RESPONSE_FLAC fixture.

core/amazon_client.py

@@ -486,12 +486,18 @@ class AmazonClient:
             "label": album.get("label", ""),
         }
         if include_tracks:
-            result["tracks"] = self.get_album_tracks(asin) or {
+            tracks_data = self.get_album_tracks(asin) or {
-                "items": [],
+                "items": [], "total": 0, "limit": 50, "next": None,
-                "total": 0,
-                "limit": 50,
-                "next": None,
             }
+            result["tracks"] = tracks_data
+            # Backfill release_date from stream tags when album metadata lacks it.
+            if not result["release_date"]:
+                items = tracks_data.get("items") or []
+                for item in items:
+                    rd = item.get("release_date") or ""
+                    if rd and len(rd) >= 4:
+                        result["release_date"] = rd
+                        break
         return result
 
     def get_album_tracks(self, asin: str) -> Optional[Dict[str, Any]]:

tests/tools/test_amazon_client.py

@@ -126,6 +126,7 @@ MEDIA_RESPONSE_FLAC = {
         "isrc": "USRC12345678",
         "trackNumber": "3",
         "discNumber": "1",
+        "date": "2024-11-22",
     },
 }
 
@@ -810,6 +811,13 @@ class TestGetAlbum:
             album = client.get_album("B0ABCDE123", include_tracks=False)
         assert "tracks" not in album
 
+    def test_release_date_backfilled_from_stream_tags(self):
+        # ALBUM_METADATA_RESPONSE has no release_date — should fall back to track date tag
+        client = self._client()
+        with patch("core.amazon_client._rate_limit"):
+            album = client.get_album("B0ABCDE123")
+        assert album["release_date"] == "2024-11-22"
+
     def test_returns_none_on_empty_albumlist(self):
         client = _make_client({"amazon-music/metadata": {"albumList": []}})
         with patch("core.amazon_client._rate_limit"):