Add delete support for XCLocalSwiftPackageReference

[Kosikowski]

Add delete support for XCLocalSwiftPackageReference

The delete method in PBXObjects was missing support for XCLocalSwiftPackageReference, causing local package references to remain as orphaned objects in the pbxproj when switching from local back to remote packages.

This adds handling for localSwiftPackageReferences in the delete method, matching the existing pattern for remoteSwiftPackageReferences.

Short description 📝

When programmatically managing Swift package dependencies in Xcode projects, switching a local package reference back to a remote package reference leaves orphaned XCLocalSwiftPackageReference objects in the project file. This occurs because PBXObjects.delete(reference:) handles remoteSwiftPackageReferences but not localSwiftPackageReferences.

This PR adds the missing delete support for local Swift package references, ensuring clean removal of these objects when they are no longer needed.

Solution 📦

The solution follows the existing pattern established for other object types in the delete(reference:) method. Specifically, it mirrors the implementation for remoteSwiftPackageReferences:

} else if let index = localSwiftPackageReferences.index(forKey: reference) {
    return _localSwiftPackageReferences.remove(at: index).value
}

Alternative approaches considered:
none

Implementation 👩‍💻👨‍💻

• Added localSwiftPackageReferences handling to PBXObjects.delete(reference:) method
• Added unit tests for add/delete operations on XCLocalSwiftPackageReference:
  • test_add_addsObjectToPBXProj — verifies adding works correctly
  • test_delete_removesObjectFromPBXProj — verifies deletion works correctly
  • test_delete_removesCorrectObject_whenMultipleExist — verifies only the targeted object is removed
  • test_delete_doesNothing_whenObjectNotInProj — verifies safe behaviour for non-existent objects
• Verified all existing tests continue to pass

Testing 🧪

All tests pass locally:

Test Suite 'XCLocalSwiftPackageReferenceTests' passed at 2026-01-29.
    Executed 8 tests, with 0 failures (0 unexpected) in 0.003 seconds