- F22: the control bar faded out from under a mouse parked on it; the hide timer
now waits while the pointer is on either band and re-arms on leave (test seen
RED by disabling the hold).
- The hand-drawn volume bar broke DESIGN.md A6 (native sliders): it had no hover,
focus, keyboard or screen-reader state. It is the Slider primitive now; a
pointer drag blurs it so Space and the arrows keep driving the player.
- The control tooltips are composited from mount (will-change: opacity): a fade
that promoted one on hover re-layered its neighbours under the player's
scale(1.25), and the whole row shimmered.