Back to Search-quality baseline: cross-source canonical (Phase 1.2, v1.2.0 candidate)

25 (query, expected_source, rationale) triples. For each: run `cupertino search "<query>" --limit 10`, extract top-1 URI, derive its source via the URI prefix, compare against expected. Aggregate: count matches; binomial test on the subset where expected source IS present in top-10.

Harness source: `/tmp/cupertino-search-eval-crosssource.py` (not yet versioned in repo). Full JSON dump (all 25 top-10 lists + sources): `/tmp/cupertino-search-eval-crosssource-20260520.json`.