Three.js 低多边形海岛螃蟹游戏：收集水晶碎片

Build a small third-person game in Three.js, delivered as a single web project with a readme. The player is a cheerful red cartoon crab on a bright low-poly tropical island: yellow sand, turquoise water, chunky palm trees, rocks, shrubs, barrels and a wooden pier. All models must be generated in code from simple shapes, with no imported assets. A chase camera follows the crab as it scurries around. The goal shown on screen is to gather seven crystal shards scattered over the island, with a small counter in the corner. Collectibles should react to the crab by lifting off the ground and flying into it as it passes. Keep the palette saturated and playful, with soft shadows under objects. Avoid repeating the same layout or props in obvious copies. Done means the crab moves smoothly, the camera follows without clipping badly through trees, and all seven shards can be collected.