Adopt scripts-to-rule-them-all: script/ entrypoints, Makefile shims, policy update (#23)

Reviewed-on: #23
Co-authored-by: sneak <sneak@sneak.berlin>
Co-committed-by: sneak <sneak@sneak.berlin>

prompts/EXISTING_REPO_CHECKLIST.md

@@ -1,6 +1,6 @@
 ---
 title: Existing Repo Checklist
-last_modified: 2026-03-10
+last_modified: 2026-07-06
 ---
 
 Use this checklist when beginning work in a repo that may not yet conform to our
@@ -45,12 +45,19 @@ with your task.
     - [ ] Python: `pyproject.toml`
     - [ ] Docs/writing: `.prettierrc`, `.prettierignore` (same URLs as above)
 
-# Makefile
+# Makefile and script/ Entrypoints
 
 - [ ] `Makefile` exists in root — reference
       `https://git.eeqj.de/sneak/prompts/raw/branch/main/Makefile`
 - [ ] Has targets: `test`, `lint`, `fmt`, `fmt-check`, `check`, `docker`,
       `hooks`
+- [ ] Target implementations live in `script/` (scripts-to-rule-them-all);
+      Makefile targets are thin shims calling them — model scripts at
+      `https://git.eeqj.de/sneak/prompts/raw/branch/main/script/<name>`
+- [ ] `script/precommit` exists and the pre-commit hook (installed by
+      `script/install-precommit`, shimmed by `make hooks`) runs it
+- [ ] README has an **Entrypoints** section documenting the `script/`
+      entrypoints and linking the standard
 - [ ] `make check` does not modify any files in the repo
 - [ ] `make test` has a 30-second timeout
 - [ ] `make test` runs real tests, not a no-op (at minimum, import/compile