Build GitHub Action (quorum-ai/quorum@v1)

[Solvely-Colin]

Publish a GitHub Action so users can add Quorum PR reviews with a simple workflow YAML (no CLI install needed).

Target spec:

# .github/workflows/quorum-review.yml
on:
  pull_request:
    types: [opened, synchronize]
jobs:
  review:
    runs-on: ubuntu-latest
    permissions:
      pull-requests: write
    steps:
      - uses: actions/checkout@v4
      - uses: quorum-ai/quorum@v1
        with:
          providers: claude,kimi
          confidence-threshold: "0.7"
          evidence: advisory
          post-comment: "true"
        env:
          ANTHROPIC_API_KEY: ${{ secrets.ANTHROPIC_API_KEY }}
          KIMI_API_KEY: ${{ secrets.KIMI_API_KEY }}

PR comments should include: synthesis, risk matrix, dissent summary, evidence report, and patch suggestions in collapsible sections.