chore: upgrade to eslint v9

Author: stee-re

.gitignore

@@ -4,6 +4,11 @@ node_modules
 *.d.ts
 *.tsbuildinfo
 !commitlint.config.js
+!commitlint.config.mjs
+!eslint.config.js
+!eslint.config.mjs
+!web-test-runner.config.js
+!web-test-runner.config.mjs
 
 ## editors
 /.idea

eslint.config.js

@@ -0,0 +1,89 @@
+import typescriptEslint from '@typescript-eslint/eslint-plugin';
+import tsParser from '@typescript-eslint/parser';
+import path from 'node:path';
+import { fileURLToPath } from 'node:url';
+import js from '@eslint/js';
+import { FlatCompat } from '@eslint/eslintrc';
+import eslintPluginTSDoc from 'eslint-plugin-tsdoc';
+import openWcConfig from '@open-wc/eslint-config';
+
+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 [
+  ...openWcConfig,
+  ...compat.extends(
+    'eslint:recommended',
+    'plugin:@typescript-eslint/eslint-recommended',
+    'plugin:@typescript-eslint/recommended',
+  ),
+  {
+    ignores: ['dist/', 'node_modules', 'coverage', 'doc'],
+  },
+
+  {
+    plugins: {
+      '@typescript-eslint': typescriptEslint,
+      'eslint-plugin-tsdoc': eslintPluginTSDoc,
+    },
+
+    languageOptions: {
+      parser: tsParser,
+    },
+
+    rules: {
+      '@typescript-eslint/no-non-null-assertion': 'off',
+
+      '@typescript-eslint/no-unused-vars': [
+        'error',
+        {
+          args: 'all',
+          argsIgnorePattern: '^_',
+          caughtErrors: 'all',
+          caughtErrorsIgnorePattern: '^_',
+          destructuredArrayIgnorePattern: '^_',
+          varsIgnorePattern: '^_',
+          ignoreRestSiblings: true,
+        },
+      ],
+      'no-use-before-define': 'off',
+      'class-methods-use-this': [
+        'error',
+        {
+          exceptMethods: ['locale'],
+        },
+      ],
+      '@typescript-eslint/no-explicit-any': [
+        'error',
+        {
+          ignoreRestArgs: true,
+        },
+      ],
+      'import-x/no-extraneous-dependencies': [
+        'error',
+        {
+          devDependencies: [
+            '**/*.test.ts',
+            '**/*.spec.ts',
+            'eslint.config.js',
+            'web-test-runner.config.js',
+          ],
+        },
+      ],
+      curly: ['error', 'all'],
+      'import-x/no-unresolved': 'off',
+      'import-x/extensions': [
+        'error',
+        'always',
+        {
+          ignorePackages: true,
+        },
+      ],
+    },
+  },
+];