Keep Documentation Current and Updated

[skyelaird]

Implement pre-commit hook and documentation checklist to ensure documentation stays current before every commit. This prevents having to "re-think" context in every chat session.

Changes:

• Add .git/hooks/pre-commit - Interactive hook that checks for documentation updates when committing code changes
• Add DOCUMENTATION_CHECKLIST.md - Comprehensive pre-commit documentation review checklist with decision tree and patterns
• Update CONTRIBUTING.md - Add documentation workflow (Section 3a) with quick checklist and rationale
• Update NEXT_STEPS.md - Document completed documentation infrastructure under Priority 5

Impact:

• Documentation updates are now systematic, not ad-hoc
• AI assistants and developers can rely on docs being current
• Context is preserved across sessions
• Reduces debugging time and improves code quality

The pre-commit hook prompts developers when they commit Python code without documentation updates, and warns about documentation files older than 30 days. Can be bypassed for trivial commits.