fix(pr-review): review interface code for correctness, with UI recall eval cases - #2017

🟢 Confidence 10/10 · safe to merge. Prompt-text only, no code paths change; the author's own eval shows no holdout gain and a possible #261 recall drop, which more repeats must settle.
_{no findings · tests not needed · risk low}

Adds an "Interface code" section to the PR review prompt and one condensed line of the same checks to the fan-out worker prompt, with nine UI eval cases. Text-only change; nothing at runtime changes shape, so it is safe to merge.

• PR_REVIEW_SYSTEM_PROMPT gains five interface-code checks (lost edits, wrong state text, aria-label, widths, client rules)
• PR_REVIEW_WORKER_PROMPT carries the same checks in one line so child reviewers apply them
• Nine UI eval cases added to the corpus, two of them held out

_{5d23c97 · Reply "won't fix" to dismiss a finding, or mention @maple-review-bot to ask about one.}