Function buttons_for_picker 

pub fn buttons_for_picker(
    repos: &[&str],
    original_msg_id: &str,
) -> Vec<(String, String)>

Build the list of (button_label, callback_data) pairs for a project picker.

original_msg_id is embedded in every callback_data so the handler can look up the original message body in pending_picks.

Button label: the last path component of the repo slug (e.g. "orch" from "gabrielkoerich/orch"), falling back to the full slug when no / is present.