modularize src

+ merge main.py and manage.py
+ move start logic to swingmusic/__main__.py
+ add a run.py on the project root

swingmusic/models/lastfm.py

@@ -0,0 +1,28 @@
+from dataclasses import dataclass
+from typing import Any
+
+
+@dataclass
+class SimilarArtistEntry:
+    artisthash: str
+    name: str
+    weight: float
+    scrobbles: int
+    listeners: int
+
+
+@dataclass
+class SimilarArtist:
+    artisthash: str
+    similar_artists: list[SimilarArtistEntry]
+
+
+    def get_artist_hash_set(self) -> set[str]:
+        """
+        Returns a set of similar artists.
+        """
+        if not self.similar_artists:
+            return set()
+
+        # INFO: 
+        return set(a['artisthash'] for a in self.similar_artists)