Revert "Created React subproject"

This reverts commit a9775f4fa5.

frontend/eslint.config.js

@@ -1,33 +0,0 @@
-import js from '@eslint/js'
-import globals from 'globals'
-import reactHooks from 'eslint-plugin-react-hooks'
-import reactRefresh from 'eslint-plugin-react-refresh'
-
-export default [
-  { ignores: ['dist'] },
-  {
-    files: ['**/*.{js,jsx}'],
-    languageOptions: {
-      ecmaVersion: 2020,
-      globals: globals.browser,
-      parserOptions: {
-        ecmaVersion: 'latest',
-        ecmaFeatures: { jsx: true },
-        sourceType: 'module',
-      },
-    },
-    plugins: {
-      'react-hooks': reactHooks,
-      'react-refresh': reactRefresh,
-    },
-    rules: {
-      ...js.configs.recommended.rules,
-      ...reactHooks.configs.recommended.rules,
-      'no-unused-vars': ['error', { varsIgnorePattern: '^[A-Z_]' }],
-      'react-refresh/only-export-components': [
-        'warn',
-        { allowConstantExport: true },
-      ],
-    },
-  },
-]