Revert js-yaml to v4.x; v5 breaks Astro/Starlight default import

Author: Copilot

package.json

@@ -14,7 +14,7 @@
   "dependencies": {
     "@astrojs/starlight": "^0.41.3",
     "astro": "^7.1.0",
-    "js-yaml": "^5.2.1",
+    "js-yaml": "^4.1.0",
     "sharp": "^0.35.3",
     "yaml": "^2.9.0"
   },