WebGPU Amazon river jelly diorama with wildlife and interactive weather

GOAL: PROMPT Build "Amazon Jelly", a single self-contained HTML file (no external requests) in the "Material Studies" series: a WebGPU diorama of a bend of the Amazon cut out of a wobbly block of jelly on a paper studio backdrop. MOTION: Plain JS + WGSL, all meshes procedural. Scene: a wide amber-brown river (shallow-water sim, murky absorption, current carrying foam and silt swirls), a village of painted stilt houses with a long pier, a floating landing and a floating shop, a football pitch, a white chapel; rainforest behind with a giant samaúma, palms and lianas; an oxbow lake with giant water lilies; a sandbar. Cut faces show candy jelly strata, then red laterite and sand beds. Life: a piranha shoal under the pier, tambaqui and an arapaima that gulps air, pink river dolphins that surface to breathe and ride the riverboat's bow wave, capybaras grazing by the lake, caimans basking (jaws agape), river turtles on a fallen trunk, toucans hopping between crowns, a pair of scarlet macaws wheeling, egrets wading, a kingfisher diving for lambari, drifting water-hyacinth rafts, villagers walking, kids playing football, a fisherman paddling a dugout. Four buttons: Feed the piranhas (a man walks out along the pier and throws scraps; a feeding frenzy with spray and a bite counter), Flood season (the river rises over the várzea for ~2 min — fish go into the drowned forest, tambaqui eat falling fruit, animals move to high ground — then falls), Riverboat (a two-deck hammock boat leaves its berth, cruises round and docks; passengers walk ashore), Downpour (squall, sheets of rain, lightning, then mist and a rainbow). Interaction: drag the water to stir it (fish flee), drag the ground to tilt the jelly block (water sloshes), tap a tree to shake down leaves and fruit, tap the pier or the boat; orbit, zoom, reset view. Panel with status lines, tallies, three flavour palettes, sliders (firmness, wave damping, breeze), pause, mute, reset; folds away when zoomed; bottom sheet on phones. Synthesised sounds only for events — no constant ambience; loops only while their event lasts. Respect prefers-reduced-motion; polite fallback card without WebGPU.