Rename /codify to /compound and codify-docs to compound-docs

The new names better reflect the compounding engineering philosophy:
each documented solution compounds your team's knowledge.

- /codify → /compound (old command shows deprecation notice)
- codify-docs → compound-docs skill
- Updated all docs, philosophy sections, and references

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

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

plugins/compounding-engineering/CLAUDE.md

@@ -35,7 +35,7 @@ agents/
 └── docs/       # Documentation agents
 
 commands/
-├── workflows/  # Core workflow commands (/plan, /review, /work, /codify)
+├── workflows/  # Core workflow commands (/plan, /review, /work, /compound)
 └── *.md        # Utility commands
 
 skills/