fix(index): remap ZoneMap search results

[lance-gatefixer]

Summary

• remap ZoneMap selected and nullable row addresses through the loaded fragment-reuse index
• preserve exact, at-most, and at-least search-result semantics during remapping
• add a multi-fragment deferred-compaction regression covering null, equality, and range predicates

Root cause

ZoneMap retained physical row addresses from index creation. Deferred-remap compaction moved those rows and supplied a fragment-reuse remapper when the index was loaded, but ZoneMap search never applied it. The exact null bitmap therefore returned stale addresses without a refinement filter and silently dropped live rows.

Validation

• cargo test -p lance test_read_zonemap_index_with_defer_index_remap -- --nocapture
• cargo test -p lance-index scalar::zonemap::tests
• cargo fmt --all -- --check
• cargo clippy --all --tests --benches -- -D warnings
• git diff --check

Fixes #8504

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.

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[lance-gatefixer]

Blocked: the current-head linux-coverage-build check is stopped by runner TLS infrastructure before repository code can build.

Remote head 58744773e3412d77b7a20dc68ed77eff916b3aca contains current main tip 67273e058b4860527dec39e7df7c8434650bb8c7; Rust run 31586073678, job 94080088712 failed in rui314/setup-mold because GitHub returned a self-signed dotcom.glb certificate whose hostname does not match github.com. I fetched and verified base ancestry, re-read the current run logs, and confirmed the other Rust build, clippy, formatting, rustdoc, and platform jobs passed, leaving no attributable code repair or safe in-scope workflow change. Please rerun the failed Rust workflow after runner networking is healthy; alternatively, a maintainer can repair or confirm the runner certificate/proxy configuration and start a fresh run.

[lance-gatekeeper]

✅ Gate recommendation: approve.

All reviewed false-negative paths are now closed. Deferred-remap search and consolidation stay in the live address domain, exact null bitmaps drive transformed counts, and ambiguous legacy singleton statistics fail safely, including Decimal zones with missing extrema.