fix(cli): always use '/' as publicPath in dev mode

packages/vant-cli/src/common/index.ts

@@ -99,4 +99,8 @@ export function setNodeEnv(value: NodeEnv) {
   process.env.NODE_ENV = value;
 }
 
+export function isDev() {
+  return process.env.NODE_ENV === 'development';
+}
+
 export { decamelize };