v0.5.0

Parquet codec and schema‑validated columnar storage

Summary

Adds a Parquet codec with explicit schema validation and new Parquet examples, plus dedicated Parquet error sentinels.

Highlights

• Introduces NewParquetCodec(schema, opts...) with schema validation at construction time.
• Adds Parquet schema/types (ParquetSchema, ParquetField, ParquetType) and compression options.
• Adds examples/parquet/ and Parquet-specific error sentinels.

Breaking Changes

• NewParquetCodec now returns (Codec, error) instead of Codec.

Upgrade Notes

• Parquet is non‑streaming: StreamWriteRecords returns ErrCodecNotStreamable; use Dataset.Write.
• When using Parquet, set the Lode compressor to NewNoOpCompressor() to avoid double compression.
• Invalid Parquet schemas now fail at construction time.

References

• docs/contracts/CONTRACT_PARQUET.md
• docs/contracts/CONTRACT_ERRORS.md

Full Changelog: v0.4.1...v0.5.0