interactive.js becomes a multi-mode engine sharing camera, motion grid,
gradient/centroid tracking and the mouse fallback. New renderers: point/line
sprites (mirror/swarm/cloth/pops) and a ping-pong trail FBO (painting).
fluid.js gains a 'touch' emitter mode fed by motion splats from the camera.
Mirror mode reforms the custom SVG/image if loaded, else a DJ LUZA wordmark.
UNPACK_ALIGNMENT set to 1 for non-multiple-of-4 single-channel uploads.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
