Refactor Differential: Abstract interfaces for pluggable differs and compression

[JusterZhu]

Summary

Extract core abstractions from GeneralUpdate.Differential to enable pluggable binary diff algorithms and compression providers.

Scope

• \IBinaryDiffer\ — abstract binary diff (Clean/Dirty)
• \ICompressionProvider\ — abstract compression (replace hardcoded BZip2)
• Refactor \BinaryHandler\ to implement \IBinaryDiffer, keeping existing BSDIFF logic intact
• Keep backward compatibility with existing \DifferentialCore\ API surface

Motivation

Currently BinaryHandler hardcodes BSDIFF algorithm + BZip2 compression. This prevents optimizing for different scenarios (smaller patches, faster decompression, streaming for large files).

Part of the Differential v2 refactor series:

• Dev #1 (this issue): Abstract interfaces
• 添加zip演示示例 #2: Brotli compression
• 麒麟V10测试完成，更新Readme文件 (KylinV10 system test passed) #3: Streaming diff core
• Add Missing File #4: Parallel pipeline
• #5: Default switch + performance report