Frontent build system is ready (#3)

* Frontent build system is ready

* Set up linter for frontend part

* move code to /src

* update db

* upd test

* remove db

* ignore .db

src/frontend/.postcssrc

@@ -0,0 +1,16 @@
+plugins:
+    postcss-smart-import: {}
+    postcss-custom-properties: {}
+    postcss-apply: {}
+    postcss-custom-media: {}
+    postcss-media-minmax: {}
+    postcss-custom-selectors: {}
+    postcss-nested-ancestors: {}
+    postcss-nesting: {}
+    postcss-nested: {}
+    postcss-color-mod-function: {}
+    postcss-color-hex-alpha: {}
+    postcss-font-family-system-ui: {}
+    cssnano: {}
+    autoprefixer:
+        browsers: ['last 2 versions', '> 1%']

src/frontend/js/app.js

@@ -0,0 +1,12 @@
+// No inspection for unused var `css` because it's used for css bundle
+// eslint-disable-next-line no-unused-vars
+import css from '../styles/main.pcss';
+
+module.exports = class Docs {
+  /**
+   * @constructor
+   */
+  constructor() {
+    console.log('CodeX Docs initialized');
+  }
+};

src/frontend/styles/main.pcss

@@ -0,0 +1,7 @@
+body {
+  font-family: system-ui, Helvetica, Arial, Verdana;
+}
+
+a {
+  color: #00B7FF;
+}