Downgrade @types/node to 20.19.19

Fix peer dependency conflict with Socket SDK.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

Author: jdalton

package.json

@@ -136,7 +136,7 @@
     "@types/js-yaml": "4.0.9",
     "@types/micromatch": "4.0.9",
     "@types/mock-fs": "4.13.4",
-    "@types/node": "24.6.2",
+    "@types/node": "20.19.19",
     "@types/npm-package-arg": "6.1.4",
     "@types/npmcli__arborist": "6.3.1",
     "@types/npmcli__config": "6.0.3",