migrate to eslint flat config

eslint.config.mjs

@@ -0,0 +1,69 @@
+import { fixupConfigRules } from "@eslint/compat";
+import { FlatCompat } from "@eslint/eslintrc";
+import js from "@eslint/js";
+import tsParser from "@typescript-eslint/parser";
+import reactRefresh from "eslint-plugin-react-refresh";
+import globals from "globals";
+import path from "node:path";
+import { fileURLToPath } from "node:url";
+
+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 [
+  {
+    ignores: ["**/dist", "**/.eslintrc.cjs"],
+  },
+  ...fixupConfigRules(
+    compat.extends(
+      "plugin:react-hooks/recommended",
+      "plugin:react/recommended",
+      "plugin:react/jsx-runtime"
+    )
+  ),
+  {
+    plugins: {
+      "react-refresh": reactRefresh,
+    },
+    languageOptions: {
+      globals: {
+        ...globals.browser,
+      },
+      parser: tsParser,
+      ecmaVersion: "latest",
+      sourceType: "module",
+      parserOptions: {
+        project: [
+          "./tsconfig.node.json",
+          "./packages/site/tsconfig.json",
+          "./packages/site/tsconfig.node.json",
+          "./packages/webgpu-waveform/tsconfig.json",
+          "./packages/webgpu-waveform/tsconfig.node.json",
+        ],
+        tsconfigRootDir: __dirname,
+      },
+    },
+
+    settings: {
+      react: {
+        version: "detect",
+      },
+    },
+
+    rules: {
+      "react/no-unescaped-entities": "off",
+      "react-refresh/only-export-components": [
+        "warn",
+        {
+          allowConstantExport: true,
+        },
+      ],
+    },
+  },
+];