chore(client): Move client app to /client

client/gatsby-config.js

@@ -0,0 +1,25 @@
+module.exports = {
+  siteMetadata: {
+    title: 'Gatsby Default Starter'
+  },
+  proxy: {
+    prefix: '/internal',
+    url: 'http://localhost:3000'
+  },
+  plugins: [
+    'gatsby-plugin-react-helmet',
+    {
+      resolve: 'gatsby-plugin-manifest',
+      options: {
+        name: 'gatsby-starter-default',
+        short_name: 'starter',
+        start_url: '/',
+        background_color: '#663399',
+        theme_color: '#663399',
+        display: 'minimal-ui',
+        icon: 'src/images/gatsby-icon.png' // This path is relative to the root of the site.
+      }
+    },
+    'gatsby-plugin-sitemap'
+  ]
+};