Add docs workflows

[recrwplay]

Adds docs GHA workflows to make sure docs always build cleanly before being merged.

• docs-pr-checks.yml - runs when a PR contains changes in docs/**
• docs-deploy-surge.yml - runs when docs-pr-checks.yml finishes. Deploys the generated HTML to a surge.sh URL for preview
• docs-teardown.yml - removes the deployed preview HTML when a PR is closed.

The docs package.json file has been updated to use the latest versions of docs packages.

The playbooks (preview.yml and publish.yml have been updated with the latest extensions).

[changeset-bot]

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Latest commit: b519b6b

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.

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