Interactive Japanese shrine diorama in WebGL with a torii, pagoda, water, and procedural…

[Note: the creator shared a partial prompt. Wording below is theirs.] GOAL: Build a single-file interactive WebGL diorama (one index.html, no build step) with Three.js r160 loaded via an import map from https://t.co/lj8MfmK18g, plus OrbitControls and BufferGeometryUtils (mergeVertices, mergeGeometries) from three/examples/jsm. Everything is procedural — no external models or textures. MOTION: CONCEPT "Torii at High Tide": a miniature Japanese shrine island inspired by Itsukushima, inside a 10×10 block of clear water with rounded edges (vertical corner radius ~0.6, top edge radius ~0.26), on a thin sand-colored base slab, on a warm washi-paper background with a soft floor shadow that fades out with distance (so long dusk shadows never streak across the page). TERRAIN (heightfield ~400×400, clipped to the rounded block, with a boundary "skirt" so the cross-section shows through the water) - Work in a local frame facing the camera (u = across, v = toward the viewer). - A forested dome-shaped hill at the back (~2.4 high), a low sandy shrine terrace at its foot, then a wide, gently sloping tidal flat in front (from ~-0.06 down to ~-0.46), dropping to ~-1.0 at the front and sides. - Two rocky granite headlands framing the bay, each with 1–2 leaning bonsai-style pines (segmented trunks + flattened canopy pads). - A flattened clearing on the hill flank for the pagoda. - Terrain shader: granite rock on steep slopes (speckled, darker wet band just above the waterline, algae-dark below it), sand with a wet line, darker wet intertidal sand below the high-tide mark, moss/grass on the hill and in patches on the terrace, snow on upward-facing surfaces in winter, procedural animated caustics under water. CPU-baked horizon AO per vertex plus canopy-cover darkening. ARCHITECTURE (merge everything into one vertex-colored mesh + one emissive "glow" mesh; write a small Builder that adds boxes/cylinders/spheres/custom geometry with a color and a transform, then mergeGeometries) - Ryōbu-style torii standing in the bay on the axis of the shrine (~1.9 tall): vermilion tapered main pillars with black base sheaths, four supporting sode-bashira legs with black caps and two connecting beams each, nuki tie beam, central strut with a dark plaque, shimaki, and a curved kasagi (extruded shape with upturned ends) with a black top layer. Pillars must end inside the shimaki, not poke through the kasagi. - Shrine on stilts over the tidal flat: plank deck (with plank-gap strips and dark edge beams) on a grid of wooden stilts reaching the seabed; a main hall and a smaller front hall (white w