[00026] Add ApplyPatch .NET wrapper and benchmarks for complete round-trip performance picture

[rorychatt]

Summary

Added a .NET ApplyPatch wrapper around the existing Rust FFI rustserver_apply_patch function, along with 6 unit tests and a new JsonApplyBenchmarks benchmark class that compares apply/patch performance across NativeJsonDiff, JsonDiffPatch.Net, and SystemTextJson.JsonDiffPatch.

API Changes

• Added NativeJsonDiff.ApplyPatch(byte[] jsonBytes, byte[] patchBytes) — applies an RFC 6902 JSON patch to a document via the Rust native library and returns the resulting JsonNode?
• Added JsonApplyBenchmarks benchmark class with NativeJsonDiff(), JsonDiffPatchNet(), and SystemTextJsonDiffPatch() benchmark methods across 8 payload categories

Files Modified

• Wrapper: src/Ivy.NativeJsonDiff/NativeJsonDiff.cs — added rustserver_apply_patch DllImport and public ApplyPatch method
• Tests: src/Ivy.NativeJsonDiff.Tests/NativeJsonDiffTests.cs — added 6 ApplyPatch tests (replace, add, remove, empty patch, null input, round-trip)
• Benchmarks: src/Ivy.NativeJsonDiff.Benchmarks/Benchmarks/JsonApplyBenchmarks.cs (new) — apply benchmarks comparing 3 libraries

Commits

• b0cf716 [00026] Add ApplyPatch .NET wrapper, tests, and apply benchmarks