Carbon Fiber 0.1.1

• Fix the macOS release build: rewrite the precompiled bundle's libruby reference to @rpath/libruby.X.Y.dylib and add @executable_path/../lib so the arm64-darwin gem loads on any Ruby install. Previously the install_name was a hardcoded path to the GitHub Actions tool-cache, causing dyld to refuse to load the bundle on user machines.
• A native binary that exists on disk but fails to load now raises LoadError instead of silently falling back to the pure-Ruby implementation.