Back to Search-quality baseline: prose / conceptual (Phase 1.5, v1.2.0 candidate)

15 prose queries, each with a regex matching a per-query enumerated valid-URI set. For each: run `cupertino search "<query>" --limit 10`, find first-relevant rank, compute P@3, P@5, any-match-in-top-3 (binary). Aggregate as means. No paired test (single-system).

Harness source: `/tmp/cupertino-search-eval-prose.py`. Full JSON dump: `/tmp/cupertino-search-eval-prose-20260520.json`.