chore: update dependencies and configuration

- Updated pillarbox to 1.14.1 on the demo page
- Updated ESLint from v8 to v9 and migrated configuration file to new format
- Updated development dependencies: Babel, Vitest, Husky, Stylelint, Sass...
- Removed unused modules like Parcel

eslint.config.mjs

@@ -0,0 +1,105 @@
+import globals from 'globals';
+import vitest from '@vitest/eslint-plugin';
+import path from 'node:path';
+import { fileURLToPath } from 'node:url';
+import js from '@eslint/js';
+import { FlatCompat } from '@eslint/eslintrc';
+
+const __filename = fileURLToPath(import.meta.url);
+const __dirname = path.dirname(__filename);
+const compat = new FlatCompat({
+  baseDirectory: __dirname,
+  recommendedConfig: js.configs.recommended,
+  allConfig: js.configs.all
+});
+
+export default [...compat.extends('eslint:recommended'), {
+  languageOptions: {
+    globals: {
+      ...globals.browser,
+    },
+
+    ecmaVersion: 'latest',
+    sourceType: 'module',
+  },
+
+  rules: {
+    complexity: ['error', {
+      max: 5,
+    }],
+
+    'function-paren-newline': ['error', 'multiline-arguments'],
+    'linebreak-style': ['error', 'unix'],
+    'max-depth': ['error', 2],
+
+    'max-len': ['error', {
+      code: 80,
+      ignoreComments: true,
+      ignoreStrings: true,
+      ignoreTemplateLiterals: true,
+      ignoreTrailingComments: true,
+      ignoreUrls: true,
+    }],
+
+    'max-lines-per-function': ['error', {
+      max: 35,
+      skipComments: true,
+    }],
+
+    'max-nested-callbacks': ['error', 3],
+    'max-statements': ['error', 10],
+    'newline-after-var': ['error', 'always'],
+
+    'no-bitwise': ['error', {
+      int32Hint: true,
+    }],
+
+    'no-cond-assign': ['error', 'always'],
+
+    'no-console': ['error', {
+      allow: ['warn', 'error'],
+    }],
+
+    'no-plusplus': ['error', {
+      allowForLoopAfterthoughts: true,
+    }],
+
+    'padding-line-between-statements': ['error', {
+      blankLine: 'always',
+      prev: '*',
+      next: 'return',
+    }],
+
+    semi: ['error', 'always'],
+    'space-before-function-paren': ['error', 'never'],
+  },
+}, {
+  files: ['packages/**/test/**', 'scripts/**/test/**'],
+
+  plugins: {
+    vitest,
+  },
+
+  rules: {
+    ...vitest.configs.recommended.rules,
+    complexity: 'off',
+    'max-lines-per-function': 'off',
+    'max-statements': 'off',
+    'max-nested-callbacks': 'off',
+    'max-len': 'off',
+    'no-conditional-expect': 'off',
+  },
+}, {
+  files: ['scripts/**/*.js'],
+
+  languageOptions: {
+    globals: {
+      ...Object.fromEntries(Object.entries(globals.browser).map(([key]) => [key, 'off'])),
+      ...globals.node,
+    },
+  },
+
+  rules: {
+    'no-console': 'off',
+  },
+}];