CI: update-stars, clear of pnpm's own stars; packageManager pins pnpm

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

package.json

@@ -6,7 +6,7 @@
   "scripts": {
     "test": "node --test \"tests/*.test.mjs\"",
     "validate": "node scripts/validate.mjs",
-    "stars": "node scripts/stars.mjs"
+    "update-stars": "node scripts/stars.mjs"
   },
   "dependencies": {
     "marked": "18.0.14",