fix: downgrade unbuild to fix cjs type output

fixes #39

Author: danielwaltz

package-lock.json

@@ -68,7 +68,7 @@
     "semantic-release": "^24.2.5",
     "standard-version": "^9.5.0",
     "typescript": "~5.8.3",
-    "unbuild": "~3.5.0",
+    "unbuild": "~3.4.2",
     "vite": "^7.0.0",
     "vitest": "^3.2.4"
   },