API Authentication Implementation

Implement API authentication for:

Authentication Method: [JWT/OAuth2/API Keys/Session-based]
Framework: [Express/FastAPI/Django/Spring/etc.]
User Storage: [DATABASE TYPE]

Requirements:
- Multi-tenancy: [YES/NO]
- Token refresh: [REQUIRED/NOT NEEDED]
- Scopes/permissions: [LIST IF APPLICABLE]
- Social login: [PROVIDERS IF NEEDED]

Please provide:
1. Complete authentication flow implementation
2. Token generation and validation code
3. Middleware/decorator for protected routes
4. Refresh token handling (if applicable)
5. Security best practices implementation
6. Error handling for auth failures