Send duplicate issue ID with close-issue intents #73054

Summary

When close-issue uses issue-intent: true and a duplicate close is routed for maintainer review, the intent request does not include the canonical issue identifier required by the API. The agent provides duplicate_of (an issue number), but the API requires duplicate_issue_id (the canonical issue's database ID). The request therefore fails with HTTP 422, and no pending suggestion is created for maintainers to accept or decline.

Reproduction

1. Configure a workflow with close-issue and issue-intent: true.
2. Have the agent request a duplicate close, including duplicate_of.
3. Use a repository automation-control policy that routes the close for review.

Actual behavior

The API rejects the intent request with duplicate_issue_id is required when suggesting a close as duplicate. The action does not create a pending suggestion, so maintainers do not see review controls and the issue does not appear in has:Suggestions.

Expected behavior

Resolve duplicate_of to the canonical issue's database ID and include it as duplicate_issue_id in the intent request for duplicate closes. The API should then create the pending suggestion for maintainer review.

Context

• Follow-up to #64443, where this correctness issue was noted as out of scope for the fail-closed fix.
• Confirmed after the fix shipped in v0.91.12: the unsafe fallback no longer occurs with Full control, but the suggestion still fails validation.
• The agent exposes duplicate_of, while the API expects duplicate_issue_id.
• Example run: https://github.com/juliamuiruri4/tailspin-toys/actions/runs/39576701604
• Related tracking investigation: https://github.com/github/plan-track-agentic-toolkit/issues/813#issuecomment-5893046249