fix(ipr): wrap comment body in object for GitHub API calls

[bokelley]

Summary

Fixes a 422 error in the IPR check CI reported on #3468. createIssueComment and updateIssueComment in scripts/ipr/github.mjs were passing the comment body text directly as options.body to request(). Since request() does JSON.stringify(body), this serialized a bare JSON string ("\"text\"") rather than the object GitHub's API requires ({"body": "text"}). GitHub responds with a 422 links/0/schema validation error.

Non-breaking justification: purely defensive fix to an internal script; no protocol or schema changes.

Pre-PR review:

• code-reviewer: approved — no blockers. Fix is consistent with how createStatus (the working method) already passes a nested object; Content-Type header remains correct.

Triage-managed PR. This bot does not currently iterate on
review comments or PR conversation threads (only on the source
issue). To unblock:

• Push fixup commits directly: gh pr checkout <num> →
  fix → push.
• Or re-trigger: comment /triage execute on the source
  issue.

See #3121
for context.

Session: https://claude.ai/code/session_01X5uXrpVmhruUCvywL4r4Gj

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