Add retry logic to handle GitHub API eventual consistency errors that
can occur after creating a new pull request. Follow-up API calls for
milestones, labels, assignees, and reviewers may fail with a 422
"Could not resolve to a node" error before the PR is fully propagated.
- Add generic `retryWithBackoff` helper in `src/utils.ts` with
exponential backoff (default 2 retries, starting at 1s delay)
- Wrap post-creation API calls in `src/github-helper.ts` with
`withRetryForNewPr()`, which only retries for newly created PRs
- Use `@octokit/request-error` `RequestError` type for precise error
matching (status 422 + "Could not resolve to a node" message)
- Add unit tests for `retryWithBackoff` covering success, retry,
exhaustion, and non-retryable error scenarios
- Update `dist/index.js` bundle and `package.json` dependencies
5f6978faf0