feat: implement AI model API proxy service

backend/app/models/__init__.py

@@ -0,0 +1,7 @@
+"""Database models."""
+from .client_key import ClientKey
+from .provider import Provider
+from .provider_key import ProviderKey
+from .request_log import RequestLog
+
+__all__ = ["ClientKey", "Provider", "ProviderKey", "RequestLog"]