Visible countdown ring + seconds number above the hero token while
auto-call runs. Host now sees exactly when the next number fires
instead of staring at a static caption.
- AutoCountdown.svelte: pure visual component, props-driven, rAF loop,
SVG ring via stroke-dashoffset, prefers-reduced-motion fallback
- MasterPanel.svelte: tickCount $state bumped per draw + on every
(re-)arm of the auto-call $effect (covers speed-slider mid-run)