test(gates): the repo-root scripts are linted and format-checked

scripts/check-node-modules.mjs and gen-changelog.mjs run in check and release but sat outside
every lane: the eslint and prettier lanes run from frontend/, and an ESLint config cannot reach
past its own directory. A contract test now holds them to the js-configs bar (recommended rules
under Node, the frontend's Prettier style); an unused variable and the old formatting are each
red. 0 lint hits; both files reformatted. Registered in docs/gates.md.

scripts/gen-changelog.mjs

@@ -70,7 +70,9 @@ if (process.argv.includes("--check")) {
     );
     process.exit(1);
   }
-  console.log(`CHANGELOG.md is current (${entries.length} releases, newest ${entries[0].version}).`);
+  console.log(
+    `CHANGELOG.md is current (${entries.length} releases, newest ${entries[0].version}).`,
+  );
 } else {
   await writeFile(TARGET, rendered, "utf8");
   console.log(`Wrote CHANGELOG.md — ${entries.length} releases, newest ${entries[0].version}.`);