modularize src

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

swingmusic/db/sqlite/migrations.py

@@ -0,0 +1,31 @@
+"""
+Reads and saves the latest database migrations version.
+"""
+
+from swingmusic.db.sqlite.utils import SQLiteManager
+
+
+class MigrationManager:
+    @staticmethod
+    def get_index() -> int:
+        """
+        Returns the latest databases migrations index.
+        """
+        sql = "SELECT * FROM dbmigrations"
+        with SQLiteManager() as cur:
+            cur.execute(sql)
+            ver = int(cur.fetchone()[1])
+            cur.close()
+
+            return ver
+
+    # 👇 Setters 👇
+    @staticmethod
+    def set_index(version: int):
+        """
+        Updates the databases migrations index.
+        """
+        sql = "UPDATE dbmigrations SET version = ? WHERE id = 1"
+        with SQLiteManager() as cur:
+            cur.execute(sql, (version,))
+            cur.close()