Bundle libIndexStore in release artifacts

[ileitch]

Summary

• bundle libIndexStore.dylib alongside the release binary so prebuilt installs can resolve it via @loader_path
• strip the Xcode toolchain rpaths that bake the builder's absolute Xcode path into release binaries
• codesign and include the bundled dylib in both the release zip and the artifact bundle

Resolves #1103

Test plan

• bash -n .mise/tasks/release
• mise r build --arch release
• run the release packaging steps against .release/periphery and verify otool -l only shows /usr/lib/swift and @loader_path
• ./.release/periphery scan --strict

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