Update config.py to use pydantic-settings and proper DB path

generated with BackendIM... (backend.im)

app/core/config.py

@@ -1,5 +1,5 @@
 from pathlib import Path
-from typing import List
+from typing import List, ClassVar
 
 from pydantic import AnyHttpUrl
 from pydantic_settings import BaseSettings, SettingsConfigDict
@@ -18,7 +18,7 @@ class Settings(BaseSettings):
     ACCESS_TOKEN_EXPIRE_MINUTES: int = 30
 
     # Database
-    DB_DIR = Path("/app") / "storage" / "db"
+    DB_DIR: ClassVar[Path] = Path("/app") / "storage" / "db"
     DB_DIR.mkdir(parents=True, exist_ok=True)
     SQLALCHEMY_DATABASE_URL: str = f"sqlite:///{DB_DIR}/db.sqlite"