docs: organize all documentation files in GitHub Pages branch

- Move remaining documentation files from main branch
- Organize files into logical directories:
  - _docs/security-patterns/ - CWE, OWASP, multi-language patterns
  - _docs/ai-integration/ - AI assistant integration guides
  - _docs/authorization/ - Authorization templates and patterns
- Remove temporary migration files and wiki-migration directory
- Clean up duplicate and temporary files
- All documentation now properly organized in GitHub Pages branch

Author: rainmana