chore(eslint): migrate to eslint 9 flat config

eslint.config.js

@@ -0,0 +1,41 @@
+import eslint from '@eslint/js';
+import tseslint from 'typescript-eslint';
+import importPlugin from 'eslint-plugin-import';
+import jsxA11y from 'eslint-plugin-jsx-a11y';
+import react from 'eslint-plugin-react';
+import reactHooks from 'eslint-plugin-react-hooks';
+
+export default tseslint.config(
+  eslint.configs.recommended,
+  tseslint.configs.recommended,
+  importPlugin.flatConfigs.recommended,
+  jsxA11y.flatConfigs.recommended,
+  react.configs.flat.recommended,
+  react.configs.flat['jsx-runtime'],
+  {
+    settings: {
+      'import/resolver': {
+        typescript: true,
+        alias: {
+          map: [['jotai-valtio', './src/index.ts']],
+        },
+      },
+      react: {
+        version: 'detect',
+      },
+    },
+    plugins: {
+      'react-hooks': reactHooks,
+    },
+    rules: {
+      ...reactHooks.configs.recommended.rules,
+      '@typescript-eslint/no-unused-vars': [
+        'error',
+        { argsIgnorePattern: '^_', varsIgnorePattern: '^_' },
+      ],
+    },
+  },
+  {
+    ignores: ['dist/'],
+  },
+);

package.json

@@ -57,16 +57,15 @@
     "singleQuote": true
   },
   "devDependencies": {
+    "@eslint/js": "^9.17.0",
     "@testing-library/jest-dom": "^6.6.3",
     "@testing-library/react": "^16.1.0",
     "@testing-library/user-event": "^14.5.2",
     "@types/node": "^22.10.2",
     "@types/react": "^19.0.2",
     "@types/react-dom": "^19.0.2",
-    "@typescript-eslint/eslint-plugin": "^8.18.1",
-    "@typescript-eslint/parser": "^8.18.1",
-    "eslint": "8.57.0",
-    "eslint-config-prettier": "^9.1.0",
+    "eslint": "^9.17.0",
+    "eslint-import-resolver-alias": "^1.1.2",
     "eslint-import-resolver-typescript": "^3.7.0",
     "eslint-plugin-import": "^2.31.0",
     "eslint-plugin-jsx-a11y": "^6.10.2",
@@ -80,6 +79,7 @@
     "react-dom": "^19.0.0",
     "ts-expect": "^1.3.0",
     "typescript": "^5.7.2",
+    "typescript-eslint": "^8.18.1",
     "valtio": "^2.1.2",
     "vite": "^6.0.4",
     "vitest": "^2.1.8"