fix(f_wait): flush UI before blocking (#25962)

src/nvim/state.c

@@ -70,7 +70,7 @@ getkey:
         update_screen();
         setcursor();  // put cursor back where it belongs
       }
-      // Flush screen updates before blocking
+      // Flush screen updates before blocking.
       ui_flush();
       // Call `os_inchar` directly to block for events or user input without
       // consuming anything from `input_buffer`(os/input.c) or calling the