Package the unsigned alpha for easier source installation

[TheGuyWithoutH]

Summary

Make the current unsigned alpha easier for technical users to install and run from source.

Why

This project is intentionally an unsigned macOS alpha, but it should still be straightforward for early adopters to get running without reading source code.

Scope

• Tighten the standalone repo layout.
• Keep the bin/mac-computer-use.js launcher stable.
• Reduce setup friction in README and smoke-test flow.
• Add any small scripts that simplify first run without pretending the project is signed or notarized.

Acceptance Criteria

• A technical user can follow the README from a fresh clone and get to a working MCP server.
• The smoke test remains the recommended setup verification path.