ludic.ui runs a frame's presses after drawing it, and what they dispatched waited for the end of the
phase - after the host had presented - so a button's change showed a frame late. Decided: drain, not a
phase per action. ui_show and ui_press drain the queue once the presses have run, so the code after
them and the frame presented next see the change; a host that runs presses some other way calls
drain_actions() before it presents.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
