chore(eslint): upgrade to eslint v9 finally

eslint.config.mjs

@@ -0,0 +1,139 @@
+import path from 'node:path';
+import { fileURLToPath } from 'node:url';
+
+import { FlatCompat } from '@eslint/eslintrc';
+import js from '@eslint/js';
+import prettier from 'eslint-plugin-prettier';
+
+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,
+});
+
+const FlatConfig = [
+  ...compat.extends(
+    'plugin:@typescript-eslint/eslint-recommended',
+    'plugin:@typescript-eslint/recommended',
+    'plugin:unicorn/recommended',
+    'next/core-web-vitals',
+    'prettier',
+  ),
+  {
+    plugins: {
+      prettier,
+    },
+
+    rules: {
+      'prettier/prettier': 'error',
+      'no-nested-ternary': 'error',
+
+      'import/order': [
+        'warn',
+        {
+          groups: ['builtin', 'external', 'internal'],
+
+          pathGroups: [
+            {
+              pattern: 'react',
+              group: 'external',
+              position: 'before',
+            },
+          ],
+
+          pathGroupsExcludedImportTypes: ['react'],
+          'newlines-between': 'always',
+
+          alphabetize: {
+            order: 'asc',
+            caseInsensitive: true,
+          },
+        },
+      ],
+
+      'unicorn/no-array-callback-reference': 'off',
+      'unicorn/no-useless-undefined': 'off',
+      'unicorn/prevent-abbreviations': 'off',
+
+      '@typescript-eslint/no-unused-vars': [
+        'error',
+        {
+          args: 'all',
+          argsIgnorePattern: '^_',
+          caughtErrors: 'all',
+          caughtErrorsIgnorePattern: '^_',
+          destructuredArrayIgnorePattern: '^_',
+          varsIgnorePattern: '^_',
+          ignoreRestSiblings: true,
+        },
+      ],
+    },
+  },
+  {
+    files: ['**/*.js?(x)'],
+
+    rules: {
+      '@typescript-eslint/no-var-requires': 'off',
+      'unicorn/prefer-module': 'off',
+    },
+  },
+  {
+    files: ['**/*.tsx', '**/*.jsx'],
+
+    rules: {
+      'unicorn/no-null': 'off',
+
+      'unicorn/filename-case': [
+        'error',
+        {
+          case: 'pascalCase',
+        },
+      ],
+    },
+  },
+  {
+    files: ['**/app/**/*.tsx'],
+
+    rules: {
+      'unicorn/filename-case': [
+        'error',
+        {
+          case: 'kebabCase',
+        },
+      ],
+    },
+  },
+  {
+    files: ['**/hooks/**/*.ts', '**/use*.ts'],
+
+    rules: {
+      'unicorn/filename-case': [
+        'error',
+        {
+          case: 'camelCase',
+        },
+      ],
+    },
+  },
+  ...compat
+    .extends(
+      'plugin:jest/recommended',
+      'plugin:jest-formatting/recommended',
+      'plugin:testing-library/react',
+    )
+    .map((config) => ({
+      ...config,
+      files: ['**/*.test.{js,jsx,ts,tsx}', '**/__mocks__/**/*.{js,jsx,ts,tsx}'],
+    })),
+  {
+    files: ['**/*.test.{js,jsx,ts,tsx}', '**/__mocks__/**/*.{js,jsx,ts,tsx}'],
+
+    rules: {
+      'unicorn/filename-case': 'off',
+    },
+  },
+];
+
+export default FlatConfig;