- OutroVideoOverlay: stagger reveal so 'Next step :' appears immediately and
'La ferme' fades in 500ms later, instead of both showing at once.
- MissionNotification: enforce 589/211 aspect-ratio + objectFit cover on the
<video> branch so webm assets (square 2000x2000) render at the same place
as the legacy PNG notifications instead of shifting the layout.
- HandTrackingTutorial: add a 5000ms fallback timeout that auto-dismisses
the overlay if MediaPipe never reports a hand (camera blocked, mouse-only
player), so the screen never stays stuck.
Tom Boullay