report: grow the Prompter port and move display_path out of the ui module

Prompter gains interactive(), select() and text() (with the Validator
type), and confirm() now propagates cancellation as Err so flows abort
instead of silently taking a default when the user hits Ctrl+C. The
terminal prompter implements the full port; the port also re-exports
the path display helper, which is pure presentation formatting used by
events and messages rather than terminal code.

src/main.rs

@@ -518,7 +518,7 @@ fn main() {
                     // print them as plain lines.
                     if !view.is_enabled() {
                         for artifact in output.artifacts() {
-                            println!("  {}", pkh::ui::display_path(&artifact));
+                            println!("  {}", pkh::report::display_path(&artifact));
                         }
                     }
                     if output.signed {