Closes the /readonly backlog card as convention-only: plan mode enforces
read-only at the permission layer; a skill cannot activate plan mode and
would imply enforcement it doesn't have.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01CLeMz48rvG3s9XpAsDxeho
jared