Gate search compatibility on result overlap

[marpaia]

Summary

• Replace exact first-page result equality with semantic identity overlap.
• Require at least 50% Jaccard overlap for at least 90% of corpus probes.
• Treat exact result sets, counts, metadata, and ranking order as diagnostic information.
• Update the focused Explorer search test to compare result identities instead of the complete rendered HTML page.
• Preserve the pinned corpus, submission parity, lifecycle, indexing, ACL, publication, removal, and expected-member requirements.

Motivation

SBOLExplorer and sbol-db use different search and ranking implementations. Exact result counts, ordering, and page contents are therefore not compatibility requirements.

The previous policy failed even though both backends passed their independent full-corpus conformance gates. The new policy tests the intended contract: both implementations must return a significantly overlapping set of relevant results without requiring identical behavior.

Jaccard overlap penalizes first pages dominated by unrelated results while allowing reasonable implementation-specific differences.

Validation

• python3 -m unittest tests/search-backends/test_compare_reports.py tests/search-backends/test_run_conformance.py
• python3 -m py_compile tests/search-backends/compare-reports.py tests/search-backends/test_compare_reports.py tests/test_functions.py tests/test_explorer_search.py tests/test_root.py
• git diff --check

All seven focused unit tests pass.