v0.4.2

Added

• Added QuackDB.SQL.explain/2 for building EXPLAIN and EXPLAIN ANALYZE statements.
• Added a development stress benchmark for local read, stream, columnar, and append scenarios.

Changed

• Improved row and nested-list materialization performance for large result sets.
• Streamed QuackDB.columnar_batches/4 through a columnar cursor path instead of materializing rows first.
• Updated large-result documentation to recommend row streaming or columnar batches for analytical results.

Fixed

• Fixed nullable fixed-width vector decoding when DuckDB stores non-decodable bytes in invalid/null slots.