Recognize Copilot's "Resolved Since Last Review" Overview Block in pr_review.py #2479

Problem

scripts/pr_review.py wait (hub main) exits 43, UNRECOGNIZED_REVIEWER_OUTPUT, on a Copilot overview carrying a "resolved since last review" summary. Its status line reports:

UNRECOGNIZED REVIEWER OUTPUT (1): ...
  summary: 3 resolved since last review  (round <head>)

The shape is a collapsible block in the ccr-overview-v2 review body. It lists the threads that earlier rounds raised and that are now resolved, each as a severity badge and a link to its thread:

<details>
<summary><strong>3 resolved since last review</strong></summary>

- <picture>...Medium severity...</picture> [Finding title](#discussion_r<id>)
</details>

In the round that showed it, the block sat between **0 open findings** and a Previously missed (3) block, which the script already reads. The block carries no finding of its own: every entry links to a thread that is already resolved.

Done when

• pr_review.py recognizes the "N resolved since last review" block as informational, so it neither counts its entries as findings nor fails the round as unrecognized.
• A fixture of the shape, with constructed titles and ids, covers it.