Cargo custom subcommand for the Operi tool framework.

This binary implements cargo operi, providing a CLI for:

• Creating new Operi tool projects (new)
• Building Operi tools (build)
• Running tool servers (serve)

Command Structure

The CLI follows Cargo's convention for custom subcommands, using a two-level parsing structure:

• cargo operi <command> - Top-level invocation
• Subcommands: new, build, serve