improve dist chunks structure

Moving all js assets into _nuxt/js and css assets into _nuxt/css

lib/common/options.js

@@ -154,11 +154,11 @@ Options.defaults = {
     uglify: {},
     publicPath: '/_nuxt/',
     filenames: {
-      css: 'vendor.[contenthash].css',
-      manifest: 'manifest.[hash].js',
-      vendor: 'vendor.[chunkhash].js',
-      app: 'app.[chunkhash].js',
-      chunk: '[name].[chunkhash].js'
+      css: 'css/[name].[contenthash].css',
+      manifest: 'js/manifest.[hash].js',
+      vendor: 'js/vendor.[chunkhash].js',
+      app: 'js/app.[chunkhash].js',
+      chunk: 'js/[name].[chunkhash].js'
     },
     vendor: [],
     plugins: [],

test/with-config.test.js

@@ -54,7 +54,7 @@ test('/ (custom app.html)', async t => {
 
 test('/ (custom build.publicPath)', async t => {
   const { html } = await nuxt.renderRoute('/')
-  t.true(html.includes('src="/test/orion/vendor.'))
+  t.true(html.includes('src="/test/orion/js/vendor.'))
 })
 
 test('/ (custom postcss.config.js)', async t => {