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

apps/mcp-server-standalone/README.md

@@ -88,9 +88,17 @@ Once connected, the agent should:
 If you use external agents through this MCP server, you may add one short instruction line to your agent memory file (`AGENTS.md`, `CLAUDE.md`, etc.) as optional reinforcement:
 
 ```md
+## RA-H Graph Memory
+
 Retrieve relevant RA-H context before substantive work, search before creating, and keep durable writeback prompts brief and confirmation-gated.
 ```
 
+Install or refresh that guidance without replacing the rest of the memory file:
+
+```bash
+npx -y ra-h-mcp-server@latest install-rules --client codex --target . --yes
+```
+
 RA-H should still work well without this line. The MCP tools, server instructions, skills, and docs are meant to carry the core behavior on their own.
 
 Do not create contradictory instruction files. Prefer one short reinforcement line over a pile of overlapping guidance.