fix: preserve agent memory files when installing RA-H rules

- Add RA-H graph memory as a marked section instead of replacing files
- Make install-rules idempotent for AGENTS.md and CLAUDE.md
- Document the demo-safe memory file setup command

Generated with Claude Code

README.md

@@ -217,6 +217,8 @@ If you need a frozen version for debugging, pin it explicitly and restart the cl
 Suggested snippet:
 
 ```md
+## RA-H Graph Memory
+
 You are helping build a thoughtful graph of atomic units of context.
 
 - Use `queryNodes` for direct lookup of a specific existing node.
@@ -226,6 +228,12 @@ You are helping build a thoughtful graph of atomic units of context.
 - Preserve the user's wording in `source` for user-authored ideas unless they explicitly want a rewrite.
 ```
 
+Or install that guidance into the repo memory file:
+
+```bash
+npx -y ra-h-mcp-server@latest install-rules --client codex --target . --yes
+```
+
 Available tools:
 
 | Tool | What it does |