[BenCodez]

Summary

Continue the reward cleanup by extracting several cohesive responsibilities from RewardHandler into focused classes under com.bencodez.advancedcore.api.rewards.

Changes

• add RewardLoader
  • reward folder management
  • reward file discovery/name normalization
  • default/example reward setup
  • reward-file loading and directly-defined reward file handling
• add RewardValidator
  • valid reward path state
  • reward-content checks
  • directly-defined reward file conflict checks
• add SubRewardResolver
  • directly-defined sub-reward discovery
  • recursive traversal
  • cycle protection for repeated sub-reward paths
• add RewardInjectionRegistry
  • injected rewards and requirements
  • reward placeholders
  • built-in registration
  • stable priority sorting
• keep RewardHandler as the public compatibility facade with the same existing methods delegating to the focused services
• keep reward execution logic in RewardHandler for a later focused executor refactor
• add RewardServicesTest coverage for loader discovery, injection ordering, validator facade behavior, and recursive sub-reward protection

All new classes are under api.rewards, matching the current package layout.

This is primarily a behavior-preserving organization refactor, with the intentional correctness improvement that recursive sub-reward discovery is bounded instead of recursing indefinitely.