fix(ci): verify comment author before updating/deleting impact comment

[carlos-alm]

Summary

• Greptile flagged (Confidence 3/5, on PR fix(ci): add non-blocking reminder for non-closing issue references in PRs #2351) that closing-keyword-check.yml's sticky-comment lookup selected an existing comment purely by body.includes(marker), with no check that the comment was authored by the workflow's own bot account — a PR participant could plant the marker text in their own comment and have it silently overwritten/deleted by a later run.
• codegraph-impact-comment.yml has the exact same pattern, pre-dating fix(ci): add non-blocking reminder for non-closing issue references in PRs #2351: comments.find(c => c.body.startsWith('## Codegraph Impact Analysis')).
• Fix: add the same c.user.login === 'github-actions[bot]' check fix(ci): add non-blocking reminder for non-closing issue references in PRs #2351's fix already applies to closing-keyword-check.yml.

Test plan

• YAML syntax validated
• No existing tests reference this workflow file (not part of the TS/JS test suite — a .github/workflows/*.yml change, not application code)
• Confirmed no other workflow files have the same unguarded pattern (grep across .github/workflows/)

Closes #2352

[greptile-apps]

Greptile Summary

This PR prevents participant-authored comments from being mistaken for the workflow’s sticky impact comment.

• Restricts impact-comment lookup to comments authored by github-actions[bot]
• Preserves creation and update behavior for comments produced by the workflow’s existing token

Confidence Score: 5/5

The PR appears safe to merge with no actionable issues identified.

The workflow’s automatic GitHub token creates comments as github-actions[bot], so the added author predicate continues to find legitimate sticky comments while preventing participant comments containing the marker from being updated.

Important Files Changed

Filename	Overview
.github/workflows/codegraph-impact-comment.yml	Safely narrows the sticky-comment lookup to the workflow bot’s comments without changing the workflow’s own comment identity or update path.

_{Reviews (1): Last reviewed commit: "fix(ci): verify comment author before up..." | Re-trigger Greptile}