2898

Added

• BPSPatcherTests — comprehensive XCTest coverage for all four BPS action types (SourceRead, TargetRead, SourceCopy, TargetCopy), CRC32 verification pass/fail, TargetCopy forward-reference guard, and invalid file/header handling; uses self-contained synthetic Data fixtures.
• UPSPatcherTests — unit tests covering single-hunk XOR, multi-hunk disjoint runs, bidirectional (reverse) patching, size-changing patches, truncated-patch rejection, source-size mismatch, and patch/source/output CRC rejection.

Fixed

• PatchCache Linux compatibility — wrapped CryptoKit import in #if canImport(CryptoKit) with a CRC32-based fallback so PVPatching builds and tests run on Linux CI.