feat: add settings and async db engine

backend/app/config.py

@@ -0,0 +1,13 @@
+from pydantic_settings import BaseSettings, SettingsConfigDict
+
+
+class Settings(BaseSettings):
+    model_config = SettingsConfigDict(env_file=".env", extra="ignore")
+
+    database_url: str
+    ollama_base_url: str
+    session_secret: str
+    port: int = 7777
+
+
+settings = Settings()