Remove Lance v0.30.0 vector search workaround when bug is fixed

[jayscambler]

Context

Lance v0.30.0 has a confirmed bug that causes "Task was aborted" errors when performing vector search on small datasets. This is due to a Rust panic with error: "range end index 3 out of range for slice of length 0".

Bug report: lance-format/lance#2464

Current Workaround

We've implemented a workaround in contextframe/frame.py in the _knn_table() method that catches the error and returns empty results with a warning.

Action Required

When Lance releases a fix for this bug:

1. Update the pylance dependency to the fixed version
2. Remove the try-catch workaround in _knn_table() method
3. Re-enable the skipped vector search tests:
   • test_knn_search_basic
   • test_search_result_scores
   • test_empty_vector_handling

Files to Update

• contextframe/frame.py (remove workaround in _knn_table())
• tests/integration/test_vector_search.py (remove @pytest.mark.skip decorators)
• pyproject.toml (update pylance version requirement)

Notes

• The bug affects vector search on datasets with fewer than ~10 rows
• Full-text search test is skipped for a different reason (requires inverted index)
• Other vector search tests pass without issues

[linear]

CFOS-45 Remove Lance v0.30.0 vector search workaround when bug is fixed