NPM Packages Release fails on main with E404: @rainlanguage/raindex needs initial publish #2602

Problem

The NPM Packages Release workflow on main failed on the soldeer-migration merge commit (262bd6c99) with:

npm error code E404
npm error 404 Not Found - GET https://registry.npmjs.org/@rainlanguage%2fraindex - Not found
npm error 404 The requested resource '@rainlanguage/raindex@0.0.1-alpha.238' could not be found or you do not have permission to access it.

@rainlanguage/raindex doesn't exist on npm yet — the package was renamed from @rainlanguage/orderbook to @rainlanguage/raindex (per the "Rename packages/orderbook to packages/raindex" commit). The release workflow's pre-publish version check 404s because the new name has never been published.

Failing run: https://github.com/rainlanguage/raindex/actions/runs/26661621214

Resolution options

1. Initial publish — run npm publish --access public once for @rainlanguage/raindex@0.0.1-alpha.238 to create the package on the registry; subsequent autopublish runs will then succeed. Requires the org NPM_TOKEN with publish rights.
2. Workflow tweak — make the release workflow treat the registry 404 as "no published versions yet -> publish the initial version" so the first publish doesn't need a manual bootstrap.

Originating from #2586 (soldeer migration), which merged with everything else green; this is the only post-merge red on main.