docs(release): support release-line docs refresh

[dc-tec]

Summary

Adds the missing release-line docs workflow for patch releases. Patch releases still reuse the existing X.Y.0 Docusaurus version, but docs fixes that apply to a patch release can now refresh that existing release-line snapshot with make docs-refresh-version DOCS_VERSION=X.Y.0.

This also updates the 0.2.x versioned docs with the plugin behavior shipped in 0.2.1, labels release-line docs as 0.2.x and 0.1.x in the version dropdown, and adds a CI guard for PRs targeting release-* branches that change source docs without touching the matching versioned snapshot.

Related Issues

Related to the 0.2.1 release follow-up and #395.

Type of Change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation update
• Refactor (code improvement/cleanup)
• CI, release, or build tooling
• Other maintenance

Risk and Compatibility

Low runtime risk; this only changes docs, docs tooling, and CI routing. The public docs paths remain stable: 0.2.x still serves from /docs, and 0.1.x still serves from /docs/0.1.0. Only the visible version labels change to represent release lines rather than exact patch versions.

Verification

• node --check website/scripts/snapshot-version.mjs && node --check website/scripts/refresh-version.mjs
• ./bin/actionlint .github/workflows/*.yml
• npm --prefix website run typecheck
• temp-tree execution of website/scripts/refresh-version.mjs 0.2.0, verifying versions.json order stays 0.2.0,0.1.0
• npm --prefix website run build
• npx --prefix website playwright install chromium
• npm --prefix website run test:e2e
• git diff --check
• pre-push make lint-ci

Reviewer Notes

The refresh command intentionally uses the currently checked-out docs as the source. For patch releases, run it from the relevant release branch, not from main, so 0.3.0-only docs do not leak into the 0.2.x snapshot.

Checklist

• My code follows the project style guide.
• I have performed a self-review of my own code.
• I have added or updated tests, or explained why tests are not needed.
• I have updated documentation, or explained why docs are not needed.
• I have updated generated artifacts, or confirmed none are affected.
• I have checked that this change does not log or expose secrets, tokens, credentials, keys, or raw Secret data.
• I have run the relevant local checks, or documented why they were not run.
• Any dependent changes have been merged, published, or clearly called out.