Replace the vendored MCAP Zstd chunk writer's ZSTD_compress2-based path with ZSTD_compressCCtx and keep the selected compression level on the wrapper state.
The previous implementation crashed in Debug and real zed_svo_to_mcap runs on this machine when the first compressed chunk was flushed with --mcap-compression zstd. The same exports succeeded with none and lz4, which narrowed the failure to the shared vendored MCAP Zstd path rather than exporter sync logic.
Also extend mcap_multi_record_tester to accept a compression argument so the Zstd path can be exercised directly during regression testing.
Verified with:
- ./build-debug/bin/mcap_multi_record_tester /tmp/mcap_multi_zstd_test.mcap zstd
- ./build-debug/bin/zed_svo_to_mcap --input jump/experiment/2/2026-03-18T11-27-15/2026-03-18T11-27-15_zed1.svo2 --output /tmp/zed1_single_zstd_fixed.mcap --mcap-compression zstd --end-frame 1
- ./build-debug/bin/zed_svo_to_mcap --segment-dir jump/experiment/2/2026-03-18T11-27-15 --output /tmp/multi_zstd_fixed.mcap --mcap-compression zstd --end-frame 1
crosstyan