REFACTOR: Remove Obsolete Enhancement Package + Complete Architecture Cleanup

Remove entire enhancement package (10+ classes) that was unused and obsolete:
- MetaDataEnhancementService and related infrastructure
- DatabaseAttributeProvider, IOAttributeProvider, ValidationAttributeProvider
- TemplateBasedEnhancer and example code
- ServiceLoader registrations for enhancement services

This enhancement system was designed to replace TypesConfig but became obsolete
when the simpler MetaDataTypeRegistry + Constraint system was implemented.
No actual usage found in codebase - only example/documentation references.

Benefits: Simplified architecture, reduced maintenance burden, cleaner codebase.
Full project compilation verified after removal.

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

Author: dmealing