[chernser]

Summary

Backport PR #3303 and #3305

Checklist

Delete items not relevant to your PR:

• Closes #
• Unit and integration tests covering the common scenarios were added
• A human-readable description of the changes was provided to include in CHANGELOG
• For significant changes, documentation in https://github.com/ClickHouse/clickhouse-docs was updated with further explanations or tutorials

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Note

Low Risk
Localized compression buffer sizing fix with no public API changes beyond correct behavior; slightly larger per-stream buffers is expected.

Overview
Fixes client-v2 INSERT failures when compressClientRequest(true) is on and a full 64 KiB block does not shrink under LZ4 or ZSTD (e.g. random data), which previously threw maxDestLen is too small / destination buffer too small because the compressed buffer matched the uncompressed block size.

The base CompressedBlockOutputStream now takes an explicit max compressed buffer size; LZ4 and ZSTD subclasses set it via LZ4Compressor.maxCompressedLength and Zstd.compressBound instead of assuming compressed output never exceeds the input block. New round-trip tests cover full-block compressible and incompressible payloads for both codecs, and CHANGELOG documents the 0.11.0 regression (#3302).

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