粒子爆発！WebGPU コンピュートシェーダー入門

Create an interactive WebGPU compute shader playground that simulates a particle explosion. Use a simple canvas (not WebGPU canvas) to render particles as dots. The page should show 'WebGPU Compute Shader: Particle Explosion' header, a small info section explaining what's happening, and a button to trigger a new explosion. The explosion should start from the center and particles fly outward with velocity, color, and lifetime. Use a JavaScript fallback if WebGPU is not available. Use no external libraries beyond CDN (Swiper, GSAP, AOS are not needed). Keep the code minimal but functional.