temporalio/nex-gen — reverse-engineered prompt

Build me an experimental Rust command line tool that reads a WIT file and generates Nexus operation bindings for Python, TypeScript, Go, and dotnet. The WIT file should be the source of truth for the public API, and protobuf descriptor input should be optional, only needed for proto backed models or when scaffolding WIT from an existing RPC.

I want the generated code to feel native in each language, with data types, wrapper methods for calling Temporal workflow operations, and service and operation metadata where that is supported. It should understand WIT directives for things like endpoint names, namespaces, support files, flattened inputs, output transforms, warnings, and resource method bindings.

Please include a few example WIT inputs, like a simple user service, a broader type coverage example, workflow start examples, and a roundtrip example. I also want commands to rebuild examples, inspect the prepared WIT workspace, and run validations similar to CI. Keep it clearly marked as experimental, and make generated output easy to format in each target language. Look up current docs online if you need to.