Function main 

pub fn main() -> ExitCode

Run the CLI over the process arguments and map the outcome onto an exit code.

cfg(not(test)) keeps this out of the unit tier’s coverage report. A test cannot execute it: cargo test replaces a binary’s main with the harness’s own, and calling it directly would run the real CLI over the harness’s argv — cargo test install would write to the repo. It carries no decision to cover either; [report] holds all of them and the e2e tier runs the real binary. Only the process-boundary argv read lives here.