fix(fusion): bound moment components to shared overlapping interval (#87)

[Muhammad-AbdullahGhani]

Related issue

Closes #87

Summary

When grouping search hits into moments in _connected_components, VidXP previously combined hits whenever their time ranges touched or overlapped (hit.start <= current_end, with current_end = max(current_end, hit.end)). This transitive interval chaining caused a single bridging hit spanning two otherwise separate moments (e.g. A overlaps B and B overlaps C, but A and C are disjoint) to collapse into one broad moment.

This change bounds each moment component to hits that share a common overlapping interval (current_overlap_end = min(current_overlap_end, hit.end)). Nearby duplicate hits covering the same scene or action still combine, while disjoint moments bridged by a longer hit remain separate occurrences.

Validation

• pytest tests/test_search_fusion.py -p no:asyncio (5 passed in 0.27s, including regression test test_bridging_hit_does_not_merge_separate_moments and test_nearby_duplicate_hits_combine_into_one_moment)
• pytest tests/test_query_service.py tests/test_evidence_delivery.py -p no:asyncio (23 passed in 1.23s)
• ruff check src/vidxp/search_fusion.py tests/test_search_fusion.py (All checks passed)
• ruff format --check src/vidxp/search_fusion.py tests/test_search_fusion.py (2 files already formatted)