Function add_package 

pub fn add_package(
    registry_root: &Path,
    name: Option<&str>,
    repo: Option<&str>,
) -> Result<(), Error>

Adds a new package definition to the registry.

This creates a new directory for the package and a template .pkg.lua file. If name or repo are not provided, it prompts the user for input.

Errors

Returns an error if:

• The path is not a Zoi registry.
• Package name or repository tier are not provided.
• The package directory cannot be created.
• The package already exists.