Refactor backend to import/export syntax and update deps

crabfit-backend/.eslintrc.js

@@ -0,0 +1,50 @@
+module.exports = {
+  'env': {
+    'es2021': true,
+    'node': true
+  },
+  'extends': 'eslint:recommended',
+  'overrides': [
+  ],
+  'parserOptions': {
+    'ecmaVersion': 'latest',
+    'sourceType': 'module'
+  },
+  'rules': {
+    'indent': [
+      'error',
+      2
+    ],
+    'linebreak-style': [
+      'error',
+      'unix'
+    ],
+    'quotes': [
+      'error',
+      'single'
+    ],
+    'semi': [
+      'error',
+      'never'
+    ],
+    'eqeqeq': 2,
+    'no-return-await': 1,
+    'no-var': 2,
+    'prefer-const': 1,
+    'yoda': 2,
+    'no-trailing-spaces': 1,
+    'eol-last': [1, 'always'],
+    'no-unused-vars': [
+      1,
+      {
+        'args': 'all',
+        'argsIgnorePattern': '^_',
+        'ignoreRestSiblings': true
+      },
+    ],
+    'arrow-parens': [
+      'error',
+      'as-needed'
+    ],
+  }
+}