fix: keep only one reference of xcframeworks when spm enabled

[hurali97]

Summary

This fixes the duplicate xcframeworks being generated when --add-spm-package is enabled. With this option, we see one instance of xcframeworks under spm-artifacts and other under package/build.

Test plan

Before:

After:

[Copilot]

Pull request overview

This PR fixes duplicated .xcframework artifacts when generating a local Swift Package Manager package (--add-spm-package) by moving XCFrameworks into spm-artifacts instead of copying them, so only a single set of artifacts remains.

Changes:

• Switch XCFramework handling from copy (fs.cpSync) to move (fs.renameSync) during SPM artifact preparation.
• Update generated README guidance to match the new spm-artifacts/ layout.
• Update unit tests to assert the source .xcframework directories are removed after SPM preparation.

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated no comments.

File	Description
packages/cli/src/brownfield/utils/prepareLocalSpmArtifacts.ts	Moves XCFrameworks into spm-artifacts to eliminate duplicate artifact copies.
packages/cli/src/brownfield/utils/createLocalSpmPackage.ts	Updates README instructions to refer to the spm-artifacts directory.
packages/cli/src/brownfield/utils/tests/prepareLocalSpmArtifacts.test.ts	Updates assertions to verify XCFrameworks are moved (source removed) and signatures normalized.
packages/cli/src/brownfield/utils/tests/createLocalSpmPackage.test.ts	Updates assertions to verify the original XCFramework path no longer exists after package creation.

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[adamTrz]

Thanks! 🎉