Add tests for sound repository, user OAuth repository, credit service, and credit decorators

- Implement comprehensive tests for SoundRepository covering CRUD operations and search functionalities.
- Create tests for UserOauthRepository to validate OAuth record management.
- Develop tests for CreditService to ensure proper credit management, including validation, deduction, and addition of credits.
- Add tests for credit-related decorators to verify correct behavior in credit management scenarios.

tests/conftest.py

@@ -13,8 +13,10 @@ from sqlmodel import SQLModel, select
 from sqlmodel.ext.asyncio.session import AsyncSession
 
 from app.core.database import get_db
+from app.models.credit_transaction import CreditTransaction  # Ensure model is imported for SQLAlchemy
 from app.models.plan import Plan
 from app.models.user import User
+from app.models.user_oauth import UserOauth  # Ensure model is imported for SQLAlchemy
 from app.utils.auth import JWTUtils, PasswordUtils