fix: advance _row_last_updated_at_version for UPDATE COLUMNS FROM

[jerryjch]

Lance dependency — required to compile

• Depends on fix(java): expose updatedFragmentOffsets on Update operation for RewriteColumns lance#6748, which adds
  Update.Builder.updatedFragmentOffsets(...) / Update.updatedFragmentOffsets() and JNI
  FromJava + IntoJava so the driver commit passes matched offsets into Rust.

Bump lance.version in pom.xml to a release that includes
lance#6748 before building or merging this PR; otherwise build fails on the new API calls.

Summary

• Fixes UPDATE COLUMNS FROM: bump _row_last_updated_at_version for matched rows #418.
• UpdateColumnsWriter.processFragment: after each fragment.updateColumns() call, reads
  result.getUpdatedRowOffsets() and accumulates a Map<Long, long[]> of fragment id →
  matched physical row offsets.
• TaskCommit: carries the per-fragment offset map alongside the existing
  updatedFragments and fieldsModified fields.
• UpdateColumnsBackfillBatchWrite.commit(): merges offset maps from all task commits and
  passes them to Update.builder().updatedFragmentOffsets(...). Lance's build_manifest
  then calls the partial _row_last_updated_at_version refresh only for the matched rows,
  leaving unmatched rows and untouched fragments unchanged.
• BaseUpdateColumnsBackfillTest: flips
  testUpdateColumnsPreservesCreatedAtAndAdvancesLastUpdatedWithStableRowIds from the
  "known gap" pin (assertEquals, no change) to the correct assertion
  (assertTrue(after > before)); updates Javadoc accordingly.

Background

UPDATE COLUMNS FROM rewrites column data in place via Lance's Operation::Update with
RewriteColumns mode. Lance's build_manifest can partially refresh
_row_last_updated_at_version for only the matched rows — but only when the
updated_fragment_offsets map is non-empty on the commit. Previously
UpdateColumnsBackfillBatchWrite never populated this map, so the partial refresh never
activated and _row_last_updated_at_version stayed stale after every UPDATE COLUMNS
commit, breaking CDF consumers.

The matched row offsets are already computed inside Lance during fragment.updateColumns()
and surfaced via FragmentUpdateResult.getUpdatedRowOffsets() (lance#6650). The missing
piece was wiring those offsets from the executor task result through TaskCommit to the
driver commit, and then setting them on the Update operation — which this PR does.

Test plan

• BaseUpdateColumnsBackfillTest#testUpdateColumnsPreservesCreatedAtAndAdvancesLastUpdatedWithStableRowIds
  — creates a stable-row-id table, runs UPDATE COLUMNS over all rows, and asserts
  _row_last_updated_at_version strictly increases for each row while
  _row_created_at_version is unchanged.

[jerryjch]

cc @hamersaw