chore: add sync-prs-to-linear action

[dielduarte]

Adds the sync-prs-to-linear workflow to automatically sync open external contributor PRs to Linear daily.

---

Summary by cubic

Adds a scheduled GitHub Actions workflow to sync open external-contributor PRs to Linear every day. Keeps Linear in sync with GitHub and addresses ENG-4902.

• New Features
  • New workflow .github/workflows/sync-prs-to-linear.yml runs daily at 10:00 UTC and supports manual runs.
  • Uses resend/public-shared-workflows/.github/actions/sync_prs_to_linear to create/update Linear issues from open PRs.
  • Requires secrets LINEAR_API_KEY and LINEAR_TEAM_ID; uses github.token.
  • Scoped permissions: pull-requests: write, issues: write; default contents: none.

^{Written for commit a35c25d. Summary will update on new commits.}

[cubic-dev-ai]

1 issue found across 1 file

Confidence score: 4/5

• This PR looks safe to merge with minimal risk; the noted concern is a permission/configuration check rather than a confirmed functional defect.
• In .github/workflows/sync-prs-to-linear.yml, the new Linear sync path depends on LINEAR_API_KEY scopes through a shared action, so insufficient permissions could cause workflow failures at runtime.
• Given the medium severity (5/10) and good confidence (7/10), this is a practical validation item before or right after merge, not an obvious merge blocker.
• Pay close attention to .github/workflows/sync-prs-to-linear.yml - verify LINEAR_API_KEY has the required API permissions for all SDK operations used by the sync action.

Prompt for AI agents (unresolved issues)

Check if these issues are valid — if so, understand the root cause of each and fix them. If appropriate, use sub-agents to investigate and fix each issue separately.


<file name=".github/workflows/sync-prs-to-linear.yml">

<violation number="1" location=".github/workflows/sync-prs-to-linear.yml:22">
P2: Custom agent: **API Key Permission Check SDK Methods**

New sync workflow introduces Linear API usage via a shared action — confirm existing `LINEAR_API_KEY` has required permissions for the operations performed by `sync_prs_to_linear`</violation>
</file>

_{Reply with feedback, questions, or to request a fix. Tag @cubic-dev-ai to re-run a review.}