feat: engine utils, editor and asset prefix improvements

engine/utils.ts

@@ -0,0 +1,6 @@
+export function resolveAsset(base: string, path: string): string {
+  if (!path || path.startsWith('http://') || path.startsWith('https://') || path.startsWith('data:')) return path
+  const b = base.endsWith('/') ? base.slice(0, -1) : base
+  const p = path.startsWith('/') ? path : '/' + path
+  return b + p
+}