feat(tui) /clear (#12444)

# /clear feature! 

/clear will clear your terminal while preserving the context/state of
the thread.

codex-rs/tui/src/insert_history.rs

@@ -174,6 +174,9 @@ where
     if should_update_area {
         terminal.set_viewport_area(area);
     }
+    if wrapped_lines > 0 {
+        terminal.note_history_rows_inserted(wrapped_lines);
+    }
 
     Ok(())
 }