refactor and set up authentication

app/models.py

@@ -0,0 +1,17 @@
+from typing import Optional, List
+import gspread
+from pydantic import BaseModel
+
+class GoogleFile(BaseModel):
+    file_id: str
+    file_name: str
+
+class Genre(BaseModel):
+    genre_id: Optional[int]
+    genre_name: str
+
+class Song(BaseModel):
+    song_id: Optional[int]
+    song_title: str
+    url: str
+    genres: List[Genre]