setup-rules-exlisted

Scaffold the two files that enable the `rules-ex` extended-rules system for this project. Both files are templates — they will not be overwritten if they already exist. The canonical template content lives in this skill's `assets/templates/` folder (also used by the `setup-all` skill's Phase 4 — treat it as the single source of truth and edit it there, not inline in either SKILL.md). **What gets created:** - `.claude/rules/rules-ex-authoring.md` — a native path-scoped rule that auto-injects an authoring guide whenever you Read/Edit a file under `.claude/rules-ex/`. Required so the guide fires for the *current* repo (native `.claude/rules` files only govern the repo they live in). - `.claude/rules-ex/README.md` — explains what the `rules-ex` folder is and how to author rules in it. Has no `paths:` front matter intentionally, so the hook ignores it. --- ## Steps 1. Read `.claude/rules/rules-ex-authoring.md`. - If it already exists, display its path and current contents, then note it was left unchanged. - If it does not exist, read `assets/templates/rules-ex-authoring.md` (in this skill's folder) and write its exact contents to `.claude/rules/rules-ex-authoring.md`. 2. Read `.claude/rules-ex/README.md`. - If it already exists, display its path and current contents, then note it was left unchanged. - If it does not exist, read `assets/templates/rules-ex-readme.md` (in this skill's folder) and write its exact contents to `.claude/rul