五重塔のボクセル庭園を1つのThree.jsファイルで生成、昼と夕暮れ切替

Build a procedural voxel diorama in one self-contained HTML file using Three.js, with no downloaded assets or prebuilt models. Show a floating square island garden in early spring with a tall five-tier pagoda in green, red and gold, pink and white cherry trees, pines, bamboo, a small pond with a red arched bridge, a torii gate, stone lanterns, a small tiled-roof house and scattered flowers. Generate everything from a fixed random seed so every load gives the same scene. Merge voxels into a single mesh and cull hidden faces to keep it light. Add a day and dusk lighting toggle: at dusk the sky darkens, lanterns glow and petals drift. Provide orbit by dragging, zoom by scroll or pinch, and an auto-orbit button, with a small title card showing voxel and triangle counts. Done when the scene loads quickly, looks identical on each reload and switches smoothly between day and dusk.