test(core): add hfile compression codec coverage

[slfan1989]

Description

Add dedicated unit test coverage for the HFile compression codec implementation in
crates/core/src/hfile/compression.rs.

The new tests cover:

• mapping supported HFile compression codec IDs to CompressionCodec variants
• rejecting an unknown codec ID with HFileError::UnsupportedCompression
• returning input bytes unchanged for the None codec
• successfully decompressing a GZIP payload
• returning an error for an invalid GZIP payload
• returning explicit unsupported-codec errors for LZO, Snappy, LZ4, BZIP2, and ZSTD

This is a test-only change and does not modify production behavior.

Closes #621.

How are the changes test-covered

• N/A
• Automated tests (unit and/or integration tests)
• Manual tests
• Details are described below

Added six unit tests covering codec ID parsing, successful decompression paths, and error handling paths in the HFile compression module.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 82.66%. Comparing base (0910ca7) to head (03ac3cc).

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #622      +/-   ##
==========================================
+ Coverage   82.37%   82.66%   +0.28%     
==========================================
  Files          83       83              
  Lines        6311     6311              
==========================================
+ Hits         5199     5217      +18     
+ Misses       1112     1094      -18     

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[slfan1989]

@yihua @xushiyan Could you please help review this PR? Thank you very much!