- Add module-level documentation to lib.rs with usage example
- Document Claims and AuthConfig structs with examples in auth.rs
- Add ChargingEngine struct documentation with initialization example
- Document ChargingRule, SubscriberAccount, AccountStatus, UsageEvent, UsageType, and RatingPlan with examples in types.rs
- Add CircuitState, CircuitBreakerError, and CircuitBreaker documentation with examples in circuit_breaker.rs
- Change AuthConfig::from_env() return type from Self to Result<Self, String>
- Remove default JWT_SECRET fallback, require environment variable to be set
- Add validation requiring JWT_SECRET to be at least 32 characters for security
- Replace expect() with ok_or_else in create_token timestamp calculation
- Replace expect() with map_err in DATABASE_URL environment variable loading
- Add ENFORCE_AUTH environment variable with true default to auth middleware
- Add early return when ENFORCE_AUTH=false for development/testing bypass
- Replace development comment with UNAUTHORIZED status code when no valid authentication found
- Move authentication bypass logic from end of function to environment-based check at start
- Add api_keys field to AuthConfig struct
- Parse API_KEYS environment variable as comma-separated list in from_env
- Add validate_api_key method to AuthConfig for key verification
- Add X-API-Key header check in auth_middleware before JWT validation
- Update comments to clarify development/testing mode for unauthenticated requests
- Add Claims struct with sub and exp fields for JWT payload
- Add AuthConfig struct with secret field loaded from JWT_SECRET environment variable
- Add create_token function generating 24-hour expiration tokens
- Add validate_token function for JWT verification
- Add auth_middleware for Axum with Authorization header Bearer token validation
- Allow unauthenticated requests temporarily for packet-gateway integration
nutcas3