Update vite, linter

eslint.config.js

@@ -0,0 +1,39 @@
+// @ts-check
+import js from '@eslint/js';
+import eslintConfigPrettier from 'eslint-config-prettier';
+import globals from 'globals';
+import gitignore from 'eslint-config-flat-gitignore';
+
+/**
+ * @type {import("eslint").Linter.Config[]}
+ */
+const config = [
+  gitignore(),
+  js.configs.recommended,
+  eslintConfigPrettier,
+  {
+    languageOptions: {
+      globals: {
+        ...globals.browser,
+        fathom: 'readonly',
+      },
+
+      ecmaVersion: 2020,
+      sourceType: 'module',
+    },
+
+    rules: {
+      'prefer-arrow-callback': ['error', { allowNamedFunctions: true }],
+      'prefer-const': ['error', { destructuring: 'all' }],
+      'no-var': 'error',
+    },
+  },
+  {
+    files: ['lib/*.mjs'],
+    languageOptions: {
+      globals: globals.node,
+    },
+  },
+];
+
+export default config;