test: close remaining quality verification gaps

tools/quality/verify-code-quality.mjs

@@ -1,5 +1,5 @@
 import { execFileSync } from 'node:child_process';
-import { readFileSync } from 'node:fs';
+import { existsSync, readFileSync } from 'node:fs';
 import { resolve } from 'node:path';
 
 const root = resolve(import.meta.dirname, '../..');
@@ -96,6 +96,12 @@ if (trackedAlternativeLocks) {
     `${trackedAlternativeLocks.replace(/\r?\n/g, ', ')}: npm/package-lock.json is the only supported committed dependency lock`,
   );
 }
+const presentAlternativeLocks = ['pnpm-lock.yaml', 'yarn.lock'].filter((file) => existsSync(resolve(root, file)));
+if (presentAlternativeLocks.length) {
+  violations.push(
+    `${presentAlternativeLocks.join(', ')}: remove alternative lock files; npm/package-lock.json is the only supported dependency lock`,
+  );
+}
 if (packageJson.packageManager !== 'npm@10.9.4') {
   violations.push('package.json: packageManager must pin the supported npm baseline');
 }