- Introduce a `takeoff` video entry in landing.json for each world; missing/
null entries leave the surface instantly (no regression)
- SurfaceScene.takeOff now plays the one-shot take-off clip full-screen,
hides the deck, and only then stops the scene and wakes GameScene
- Guard against a clip that never starts or runs past its duration so the
player is never stranded; finishTakeoff is idempotent
- Update surface-flow/surface-shot dev harnesses to assert and screenshot
the new take-off stage
- Re-map gas giant frames in planets.json from [0,1,2] to [3,4,5] to match
their sheet positions