feat(agents): add Claude delegation skill

Add a repository-owned Codex skill and helper for bounded Claude Code execution, model and effort selection, resumable follow-ups, and independent acceptance checks.

.codex/skills/delegate-to-claude/agents/openai.yaml

@@ -0,0 +1,4 @@
+interface:
+  display_name: "Delegate to Claude Code"
+  short_description: "Delegate scoped work to Claude Code"
+  default_prompt: "Use $delegate-to-claude to delegate this scoped task to Claude Code and review the result."