[FSSDK-12882] release pipeline update

[junaed-optimizely]

Summary

Adds GitHub Package Registry (GHR) publishing alongside the existing npm release, and a way to backfill historical versions to GHR.

Changes

• react_release.yml — on release, builds/tests/packs a single tarball once and publishes that same artifact to both npm and GHR, so both registries get identical bytes. npm publishes first; if it fails the job stops before GHR, keeping the registries in sync.
• scripts/publish.sh — shared, idempotent publish helper: skips versions already present on the target registry (safe re-runs), computes the dist-tag from the version (beta/alpha/rc/latest), and never moves latest backwards onto an older major (tags it v-latest instead).
• ghr_backfill.yml — manual (workflow_dispatch) workflow to backfill any or all npm versions into GHR by re-publishing the npm tarballs. Idempotent, with a dry-run option.

Recovery

• npm ok / GHR fails → re-run the release, or run the backfill (guard skips what's already published).
• npm fails → GHR is skipped; nothing is half-published.

Test plan

Existing tests should pass

Issues

• FSSDK-12882

[Copilot]

Pull request overview

This PR updates the @optimizely/react-sdk release tooling to make publishing repeatable across both npm and GitHub Package Registry (GHR) by introducing a shared, idempotent publish script, splitting the release workflow into separate npm/GHR jobs, and adding a manual backfill workflow for populating historical versions into GHR from npm tarballs.

Changes:

• Added scripts/publish.sh to publish idempotently to a specified registry and compute the correct dist-tag from the version.
• Refactored the release workflow to publish to npm and GHR in separate jobs using the shared publish script.
• Added a manual backfill workflow to republish npm tarballs into GHR (with optional dry-run).

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 2 comments.

File	Description
scripts/publish.sh	New registry-agnostic publish helper with version-exists guard and dist-tag selection.
.github/workflows/react_release.yml	Splits release publishing into npm and GHR jobs, both calling the shared publish script.
.github/workflows/ghr_backfill.yml	Adds manual workflow to backfill versions from npm into GHR using packed tarballs and the publish script.

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[Copilot]

Pull request overview

Copilot reviewed 3 out of 3 changed files in this pull request and generated 2 comments.

[Copilot]

Pull request overview

Copilot reviewed 3 out of 3 changed files in this pull request and generated 3 comments.

[Copilot]

Pull request overview

Copilot reviewed 3 out of 3 changed files in this pull request and generated 2 comments.

[Copilot]

Pull request overview

Copilot reviewed 3 out of 3 changed files in this pull request and generated no new comments.