added codex structure

docs/runbook.md

@@ -0,0 +1,19 @@
+# Runbook
+
+Operational runbook for this project.
+
+## Common tasks
+
+Document routine operational tasks here.
+
+## Troubleshooting
+
+Document known issues, symptoms, checks, and remediation steps.
+
+## Rollback
+
+Document rollback procedures here.
+
+## Emergency contacts
+
+Document project-specific escalation paths if appropriate.