refactor: Complete database-first migration and documentation consolidation

Major Changes:
- Remove all file-based pattern storage (MDX files deleted, content now in PostgreSQL)
- Delete obsolete scripts (add-lesson-order.ts, rules.ts)
- Remove deprecated functions (readPattern, findMdxFiles)
- Clean up generated files (skill-generator.js/d.ts)
- Consolidate all documentation into docs/ folder
- Update all code references to use database instead of files

Database Migration:
- All patterns now stored in PostgreSQL database
- Removed content/published/patterns/ directory (backed up)
- Updated all scripts to use database repositories
- Refactored MCP server, skill generators, and CLI tools

Documentation Organization:
- Moved CHANGELOG.md to docs/
- Moved all scripts documentation to docs/scripts/
- Moved all services documentation to docs/services/
- Moved release notes to docs/release/
- Created docs/DOCUMENTATION_ORGANIZATION.md

Code Updates:
- Updated ep-admin and ep-cli to remove deprecated functions
- Updated CHANGELOG.md references in release scripts
- Updated README.md to use slug-based anchor links
- Updated all documentation references

Cleanup:
- Deleted patterns-chat-app directory (moved to separate repo)
- Deleted obsolete JSON data files
- Removed legacy file-based loading functions from toolkit