Add Adler32, Crc32, and Deflate APIs

[Copilot]

Adds three new static utility classes for checksum computation and Deflate compression.

New APIs

• Adler32.Hash(Stream) / Adler32.Hash(byte[]) / Adler32.Hash(ReadOnlySpan<byte>) → uint
• Crc32.Hash(Stream) / Crc32.Hash(byte[]) / Crc32.Hash(ReadOnlySpan<byte>) → uint (IEEE 802.3 / 0xEDB88320 polynomial)
• Deflate.Compress(Stream, Stream) / Deflate.Compress(byte[]) / Deflate.Compress(ReadOnlySpan<byte>) → void / byte[]
• Deflate.Decompress(Stream, Stream) / Deflate.Decompress(byte[]) / Deflate.Decompress(ReadOnlySpan<byte>) → void / byte[]

uint checksum = Adler32.Hash("Wikipedia"u8);       // 0x11E60398
uint crc      = Crc32.Hash("123456789"u8);         // 0xCBF43926

byte[] compressed   = Deflate.Compress(data);
byte[] decompressed = Deflate.Decompress(compressed);

// Stream-based API
using var input  = File.OpenRead("data.bin");
using var output = File.Create("data.deflate");
Deflate.Compress(input, output);

Implementation notes

• Stream overloads are the primary implementations for all three classes.
• byte[] overloads delegate to the Stream overloads via MemoryStream.
• ReadOnlySpan<byte> overloads are guarded with #if !NETFRAMEWORK || NET45_OR_GREATER (consistent with existing Span usage; System.Memory is not available for net35). Adler32 and Crc32 span overloads compute directly over the span to avoid an intermediate array allocation; Deflate span overloads delegate via .ToArray().
• Crc32 uses a pre-computed 256-entry lookup table initialized once at startup.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 86.20%. Comparing base (96a1e2a) to head (c69f84d).
⚠️ Report is 1 commits behind head on prime.

Additional details and impacted files

@@            Coverage Diff             @@
##            prime      #86      +/-   ##
==========================================
+ Coverage   85.45%   86.20%   +0.75%     
==========================================
  Files          71       74       +3     
  Lines        1176     1240      +64     
  Branches      218      229      +11     
==========================================
+ Hits         1005     1069      +64     
  Misses        121      121              
  Partials       50       50              

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[Copilot]

Pull request overview

This PR introduces three new utility APIs in PowerKit for common binary operations: Adler-32, CRC-32 (IEEE 802.3), and Deflate compression/decompression, alongside unit tests to validate expected behavior.

Changes:

• Added Adler32 and Crc32 static classes with byte[] and ReadOnlySpan<byte> hashing overloads.
• Added Deflate static class with Compress/Decompress APIs for byte[] and (where available) ReadOnlySpan<byte>.
• Added test coverage for the new checksum and compression utilities.

Reviewed changes

Copilot reviewed 6 out of 6 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
PowerKit/Adler32.cs	Adds Adler-32 checksum API with Span + array overloads.
PowerKit/Crc32.cs	Adds CRC-32 checksum API with lookup table + Span + array overloads.
PowerKit/Deflate.cs	Adds Deflate compression/decompression helpers for arrays and spans (where supported).
PowerKit.Tests/Adler32Tests.cs	Validates Adler-32 known vectors and basic invariants.
PowerKit.Tests/Crc32Tests.cs	Validates CRC-32 known vectors and basic invariants.
PowerKit.Tests/DeflateTests.cs	Validates roundtrip compression/decompression and basic compression behavior.

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[Tyrrrz]

@copilot

[Copilot]

Pull request overview

Copilot reviewed 6 out of 6 changed files in this pull request and generated 8 comments.

[Tyrrrz]

@copilot do you think we could end Stream overloads for all these methods and delegate byte[] overloads to them via MemoryStream?

[Copilot]

@copilot do you think we could end Stream overloads for all these methods and delegate byte[] overloads to them via MemoryStream?

Yes, done in commit refactor: add Stream overloads as primary, delegate byte[] via MemoryStream.

• Adler32.Hash(Stream) and Crc32.Hash(Stream) are now the primary implementations (read via a 4 KB buffer loop). Hash(byte[]) wraps in a MemoryStream and delegates.
• Deflate.Compress(Stream, Stream) and Deflate.Decompress(Stream, Stream) are now the primary implementations. Compress(byte[]) / Decompress(byte[]) wrap their inputs/outputs in MemoryStream and delegate.
• The ReadOnlySpan<byte> overloads on Adler32/Crc32 still compute directly over the span (no stream overhead), and Deflate's span overloads delegate via ToArray().
• Added Stream-overload tests for all three classes, plus the previously missing Deflate ReadOnlySpan<byte> round-trip test.