Function register_problems_ex_commands 

pub fn register_problems_ex_commands(registry: &mut CommandRegistry)

Boot helper — register the :copen + :cclose ex-commands.

:copen emits AppEffect::ProblemsOpen; the host arm reads the core error list and calls create_problems_view. :cclose emits AppEffect::ProblemsClose, which the host guards to the active problems view before closing.