Deploy validated main builds to GitHub Pages

[Copilot]

GitHub Pages is introduced as the first deployment target. Deployments promote CI’s validated production artifact rather than rebuilding application assets.

• Deployment workflow
  • Triggers after successful CI push runs on main
  • Downloads the matching rad-io-dist-<SHA> artifact
  • Uploads it as a Pages artifact and deploys through the github-pages environment
  • Uses scoped Pages and OIDC permissions with serialized deployments

if: github.event.workflow_run.conclusion == 'success' &&
    github.event.workflow_run.event == 'push'

• Documentation
  • Updates CI documentation to describe GitHub Pages artifact promotion behavior.

• Fixes Setup GitHub Pages as first deployment target #305

[Copilot]

Copilot wasn't able to review any files in this pull request.

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[Copilot]

🟡 Changes recommended

The new Pages workflow is missing actions: read token permissions needed to download artifacts from a different workflow run via run-id.

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Review details

• Files reviewed: 2/2 changed files
• Comments generated: 1
• Review effort level: Lite

[alexthemitchell]

@copilot Fix the code for all comments in this review thread.

When a review comment includes a suggested change, apply the suggestion exactly.

Do not make changes beyond what is described in the linked review thread.

[Copilot]

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[Copilot]

@copilot Fix the code for all comments in this review thread.

When a review comment includes a suggested change, app...

Added actions: read to the Pages workflow permissions in aa198ac.