Per code review feedback from @objecttothis:
- Create app/Enums/RewardOperation.php with Deduct, Restore, Adjust cases
- Update Reward_lib::adjustRewardPoints() to use RewardOperation enum
instead of string parameter for operation type
- Update tests to use RewardOperation::Deduct/Restore enum values
Benefits:
- Type safety: Cannot pass invalid operation string
- IDE autocomplete support for operation types
- Compile-time error for typos instead of runtime failure
- Self-documenting code with explicit cases
