feat: publish npm RCs from prerelease releases

[Egge21M]

Description

This pull request adds prerelease npm publishing for GitHub prerelease releases using Changesets-generated RC versions.

Problem

The existing publish workflow treats all GitHub releases the same. Prerelease GitHub releases need npm prerelease versions published under the rc dist-tag, and repeated RCs need monotonically increasing rc.N versions.

Summary

• Splits stable and prerelease npm publish jobs.
• Adds an RC preparation script that advances generated Changesets prerelease versions based on existing npm RC versions.
• Publishes prerelease packages with changeset publish --tag rc.

Verification

• bunx changeset pre enter rc
• bunx changeset version
• env PATH=/tmp/coco-fake-npm:$PATH bun scripts/prepare-rc-release.ts
• bun run build
• ./node_modules/.bin/tsc --noEmit --target ES2022 --module NodeNext --moduleResolution NodeNext --strict --noUncheckedIndexedAccess scripts/prepare-rc-release.ts
• ./node_modules/.bin/prettier --check .github/workflows/publish.yml scripts/prepare-rc-release.ts
• ruby -e 'require "yaml"; YAML.load_file(".github/workflows/publish.yml", aliases: true); puts "ok"'
• git diff --check

Changeset

• No changeset added; this changes release automation only, not package runtime behavior.

[changeset-bot]

⚠️ No Changeset found

Latest commit: 1c2911b

Merging this PR will not cause a version bump for any packages. If these changes should not result in a new version, you're good to go. If these changes should result in a version bump, you need to add a changeset.

This PR includes no changesets

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