fix transient keymap consumption bug

- Fixed transient keymap consumption logic: the transient keymap is now only
  consumed when a match is found.
- Updated handle_key to retain transient keymap if no command matches, allowing
  subsequent key presses to be processed by the main keymap set.
- Added issue noting the previous unintended consumption.

Co-Authored-By: fiddlerwoaroof/git-smart-commit (gpt-oss:20b)

src/ui/app.rs

@@ -1125,7 +1125,7 @@ mod tests {
     fn enter_advance_stays_at_bottom_right() {
         let mut app = two_col_model();
         app.model.active_view_mut().selected = (2, 1);
-        app.enter_advance();
+        run_cmd(&mut app, &crate::command::cmd::EnterAdvance);
         assert_eq!(app.model.active_view().selected, (2, 1));
     }