Prepare a separately linked UI library. With no arguments, select this
package’s library or its package.metadata.pax.cartridge selection;
init!(my_ui) selects an explicit dependency.
Initializes the selected root in the current native process. run() enters
its platform application loop. Neither operation parses application arguments
or starts build tools or development servers, including with designtime.
Use init_with! to provide explicit startup options.
Prepare a UI with InitOptions: init_with!(options) or
init_with!(my_ui, options) for a separate UI dependency.
Always initializes in the current native process; never parses development
arguments or starts a workstation build/server.