Attributification [Attribute Unification]

Added

• Added conditional debug logging controlled by config option
• Added centralized AttributeUtils class for shared caching across mixins
• Added callback system for cache management on config reload

Changed

• Major optimization: Migrated to direct JSON parsing for config migration (removed deprecated classes)
• Performance: Implemented 4-level caching system (global, per-config, per-mixin, per-thread)
• Performance: Added bidirectional caching in AttributeUnifier (source→mapping and target→mapping)
• Performance: Centralized attribute ID lookups in AttributeUtils with ConcurrentHashMap caching
• Code quality: Removed code duplication by centralizing common operations in AttributeUtils
• Code quality: Eliminated redundant cache in EntityAttributeInstanceMixin (now uses AttributeUnifier.getMappingByTarget())
• Code quality: Improved recursion protection with ThreadLocal guards

Removed

• Removed deprecated AttributificationConfig class (migration now uses direct JSON parsing)
• Removed deprecated AttributeMapping class (migration now uses direct JSON parsing)