[BUG] Backfill marks PRs `mentor_verified` even when the mentor didn't approve

[Kirtan-pc]

Describe the Bug

The PR backfill pipeline (pr-backfill → upsertReviews) flips pull_requests.mentor_verified to true for any substantive review from a higher-level reviewer — including changes_requested reviews (even with an empty body) and commented reviews with a body of 20+ characters. The live webhook path (process-review-event) only sets mentor_verified: true when the review state is exactly approved. As a result, PRs that a mentor actually requested changes on are shown as "mentor verified" in the maintainer queue, analytics, and contributor reports.

Steps to Reproduce

1. Install the app on a repo and run pr-backfill (or trigger it from the maintainer "Refresh PRs" button).
2. Have a PR in that repo whose highest-level reviewer left a CHANGES_REQUESTED review (no body needed).
3. Query pull_requests for that PR.
4. See mentor_verified = true, even though the mentor never approved.

Expected Behavior

mentor_verified should only become true when the highest-level reviewer's review state is approved, matching the webhook handler (process-review-event.ts:265).

Screenshots (If applicable)

N/A

💻 Environment Details

• OS: N/A (server-side logic)
• Browser: N/A
• Version: main

[Kirtan-pc]

Hi @maintainer,

I would like to work on this issue under GSSoC 2026.

Could you please assign this issue to me?

Thank you!

[GhanshyamJha05]

@Ayush4958 i would like to work on this assign me !!