iOS: bspatch integration

[ofalvai]

Context

iOS side of #40: set up tooling and build systems to integrate the hdiffpatch library and our bspatch_bridge wrapper.

No business logic in this PR, that's in #48.

Summary of changes

• Share C code between iOS and Android at ./shared/: the vendored hdiffpatch library and our thin bspatch_bridge from Android: bspatch integration #40 moves to the shared dir. The vendored bzip2 lib remains at ./android as iOS links against the system library (-lbz2)
• Tweak the Cocoapods spec file to include the above C code and link against system bzip2. This mirrors CMakeLists.txt from the Android side.
• Unit tests that call applyPatch() directly from bspatch_bridge.h. The same test cases as in Android: bspatch integration #40
• CodePush.xcodeproj gets a new test target to run those tests.
• Now that both platforms have unit tests, add a package.json task for each, and run the new iOS unit tests in CI.

[Copilot]

Pull request overview

Introduces a shared native BSDIFF40 patching implementation intended for iOS and Android, with an iOS unit-test target and CI coverage.

Changes:

• Moves the HDiffPatch bridge and vendored sources into shared directories.
• Adds iOS patch fixtures, unit tests, project configuration, and CI execution.
• Updates Android to consume the shared implementation.

Reviewed changes

Copilot reviewed 19 out of 39 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
shared/third_party/README.md	Documents vendored HDiffPatch sources.
shared/third_party/hdiffpatch/LICENSE	Adds upstream licenses.
shared/third_party/hdiffpatch/libHDiffPatch/HPatch/patch.h	Adds patch API declarations.
shared/third_party/hdiffpatch/libHDiffPatch/HPatch/patch.c	Adds core patch implementation.
shared/third_party/hdiffpatch/libHDiffPatch/HPatch/patch_types.h	Adds patch types and stream interfaces.
shared/third_party/hdiffpatch/libHDiffPatch/HPatch/patch_private.h	Adds internal patch helpers.
shared/third_party/hdiffpatch/libHDiffPatch/HPatch/hpatch_mt/hpatch_mt.h	Adds multithreading interfaces.
shared/third_party/hdiffpatch/libHDiffPatch/HPatch/checksum_plugin.h	Adds checksum plugin API.
shared/third_party/hdiffpatch/file_for_patch.h	Adds file-stream declarations.
shared/third_party/hdiffpatch/file_for_patch.c	Adds file-stream implementation.
shared/third_party/hdiffpatch/dirDiffPatch/dir_patch/dir_patch_types.h	Adds directory patch types.
shared/third_party/hdiffpatch/decompress_plugin_demo.h	Adds bzip2 decompression support.
shared/third_party/hdiffpatch/bsdiff_wrapper/bspatch_wrapper.h	Declares BSDIFF40 patch APIs.
shared/third_party/hdiffpatch/bsdiff_wrapper/bspatch_wrapper.c	Implements BSDIFF40 patch application.
shared/diffpatch/bspatch_bridge.h	Defines the shared patch bridge API.
shared/diffpatch/bspatch_bridge.c	Implements bridge resource and error handling.
package.json	Adds native unit-test scripts.
ios/CodePushDiffPatchTests/Fixtures/wrong_old/old.dat	Adds mismatched-base fixture.
ios/CodePushDiffPatchTests/Fixtures/identical/old.dat	Adds identical-input fixture.
ios/CodePushDiffPatchTests/Fixtures/identical/new.dat	Adds identical-output fixture.
ios/CodePushDiffPatchTests/Fixtures/identical/patch.bsdiff	Adds identical-data patch fixture.
ios/CodePushDiffPatchTests/Fixtures/empty_old/old.dat	Adds empty-base fixture.
ios/CodePushDiffPatchTests/Fixtures/empty_old/new.dat	Adds expected literal output.
ios/CodePushDiffPatchTests/Fixtures/empty_old/patch.bsdiff	Adds empty-base patch fixture.
ios/CodePushDiffPatchTests/Fixtures/basic/old.dat	Adds ordinary base fixture.
ios/CodePushDiffPatchTests/Fixtures/basic/new.dat	Adds ordinary expected output.
ios/CodePushDiffPatchTests/Fixtures/basic/patch.bsdiff	Adds ordinary patch fixture.
ios/CodePushDiffPatchTests/Fixtures/bad_header/old.dat	Adds invalid-header base fixture.
ios/CodePushDiffPatchTests/Fixtures/bad_header/patch.bsdiff	Adds malformed patch fixture.
ios/CodePushDiffPatchTests/DiffPatchTests-Bridging-Header.h	Exposes the C bridge to Swift tests.
ios/CodePushDiffPatchTests/BSPatchTests.swift	Tests patch success and failures.
ios/CodePush.xcodeproj/xcshareddata/xcschemes/CodePushTests.xcscheme	Adds the shared test scheme.
ios/CodePush.xcodeproj/project.pbxproj	Configures the iOS test target.
CLAUDE.md	Documents native unit testing.
android/app/src/main/java/com/microsoft/codepush/react/diffpatch/DiffPatch.kt	Updates the bridge path reference.
android/app/src/main/cpp/third_party/README.md	Points to shared vendored sources.
android/app/src/main/cpp/CMakeLists.txt	Builds Android against shared sources.
.npmignore	Excludes iOS test sources from publishing.
.github/workflows/ci-test.yml	Runs iOS unit tests and reduces duplicate Android tests.

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[ofalvai]

This xcodeproj is really ancient and has all sorts of problems. The CodePush target doesn't even compile (missing RN headers). We'll fix this one day, but the important thing for this PR is that the tests are buildable and runnable.

[ofalvai]

Fixed, turns out it wasn't even necessary to link Foundation.framework -> removed.