update, lint, prettify everything

put backend sources into src
setup circleci
don't use react-loadable because it seems unnecessary

.eslintrc.json

@@ -1,43 +1,15 @@
 {
+  "root": true,
   "extends": [
     "eslint:recommended",
     "plugin:node/recommended",
     "plugin:jest/recommended"
   ],
-  "rules": {
-    "no-unused-expressions": [
-      "error",
-      {
-        "allowTernary": true
-      }
-    ],
-    "no-console": "warn",
-    "no-underscore-dangle": [
-      "warn",
-      {
-        "allow": ["_id"]
-      }
-    ],
-    "func-names": "off",
-    "node/no-unsupported-features/es-syntax": [
-      "error",
-      {
-        "version": ">=10.0.0",
-        "ignores": []
-      }
-    ],
-    "node/no-unsupported-features/es-builtins": [
-      "error",
-      {
-        "version": ">=10.0.0",
-        "ignores": []
-      }
-    ]
-  },
+  "rules": {},
   "parserOptions": {
     "sourceType": "module"
   },
   "env": {
     "node": true
   }
-}
+}