Add publishConfig for npm OIDC provenance

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: haydenbleasel

package.json

@@ -5,6 +5,10 @@
     "type": "git",
     "url": "https://github.com/vercel/next-forge.git"
   },
+  "publishConfig": {
+    "provenance": true,
+    "access": "public"
+  },
   "bin": {
     "next-forge": "dist/index.js"
   },