[docs]: add docs for extension zip getter

Merged
SE
12h ago
+80-4

what changed

  • adds docs for getExtensionArchive(), get_extension_archive(), ExtensionArchive()

Summary by cubic

Documents the new extension ZIP export helpers and updates the deployment guide to use them instead of the hardcoded node_modules path.

  • Adds a new "Exporting the Stagehand extension" section covering getExtensionArchive(), get_extension_archive(), and ExtensionArchive(), including upload and local Chrome installation examples.
  • Updates the deployment guide to export stagehand-extension.zip via the SDK helper before uploading.