Update gpu.js

gpu.js

@@ -1,6 +1,7 @@
 export async function initGPU(width, height) {
   if (!navigator.gpu) {
-    throw new Error("WebGPU not supported");
+    console.warn("WebGPU not supported, falling back to CPU");
+    return null;
   }
 
   const adapter = await navigator.gpu.requestAdapter();
@@ -12,8 +13,8 @@ export async function initGPU(width, height) {
     size,
     usage:
       GPUBufferUsage.STORAGE |
-      GPUBufferUsage.COPY_DST |
-      GPUBufferUsage.COPY_SRC
+      GPUBufferUsage.COPY_SRC |
+      GPUBufferUsage.COPY_DST
   });
 
   return { device, buffer };