Scroll film landing

A landing page whose hero is a film the visitor scrubs with the scroll: N stills become N-1 clips, clip k runs from stop k to stop k+1, and scroll position sets currentTime. Scroll down to go forward, up to go back. Method after midudev's Arko landing (github.com/midudev/mcp-higgsfield-landing); the engine here is its own implementation.

Contract