Update tsup to use node24 and migrate ESLint to flat config

Author: grahamc

.eslintrc.json

@@ -0,0 +1,77 @@
+import github from "eslint-plugin-github";
+import tseslint from "@typescript-eslint/eslint-plugin";
+import tsparser from "@typescript-eslint/parser";
+
+export default [
+  github.getFlatConfigs().recommended,
+  ...github.getFlatConfigs().typescript,
+  {
+    files: ["**/*.ts"],
+    languageOptions: {
+      parser: tsparser,
+      parserOptions: {
+        ecmaVersion: 9,
+        sourceType: "module",
+        project: "./tsconfig.json",
+      },
+    },
+    plugins: {
+      "@typescript-eslint": tseslint,
+    },
+    rules: {
+      "i18n-text/no-en": "off",
+      "eslint-comments/no-use": "off",
+      "import/no-namespace": "off",
+      "no-unused-vars": "off",
+      "@typescript-eslint/no-unused-vars": [
+        "error",
+        {
+          argsIgnorePattern: "^_",
+        },
+      ],
+      "@typescript-eslint/explicit-member-accessibility": [
+        "error",
+        {
+          accessibility: "no-public",
+        },
+      ],
+      "@typescript-eslint/no-base-to-string": "error",
+      "@typescript-eslint/no-require-imports": "error",
+      "@typescript-eslint/array-type": "error",
+      "@typescript-eslint/await-thenable": "error",
+      "@typescript-eslint/ban-ts-comment": "error",
+      camelcase: "error",
+      "@typescript-eslint/consistent-type-assertions": "error",
+      "@typescript-eslint/explicit-function-return-type": [
+        "error",
+        {
+          allowExpressions: true,
+        },
+      ],
+      "func-call-spacing": ["error", "never"],
+      "@typescript-eslint/no-array-constructor": "error",
+      "@typescript-eslint/no-empty-interface": "error",
+      "@typescript-eslint/no-explicit-any": "error",
+      "@typescript-eslint/no-floating-promises": "error",
+      "@typescript-eslint/no-extraneous-class": "error",
+      "@typescript-eslint/no-for-in-array": "error",
+      "@typescript-eslint/no-inferrable-types": "error",
+      "@typescript-eslint/no-misused-new": "error",
+      "@typescript-eslint/no-namespace": "error",
+      "@typescript-eslint/no-non-null-assertion": "warn",
+      "@typescript-eslint/no-unnecessary-qualifier": "error",
+      "@typescript-eslint/no-unnecessary-type-assertion": "error",
+      "@typescript-eslint/no-useless-constructor": "error",
+      "@typescript-eslint/no-var-requires": "error",
+      "@typescript-eslint/prefer-for-of": "warn",
+      "@typescript-eslint/prefer-function-type": "warn",
+      "@typescript-eslint/prefer-includes": "error",
+      "@typescript-eslint/prefer-string-starts-ends-with": "error",
+      "@typescript-eslint/promise-function-async": "error",
+      "@typescript-eslint/require-array-sort-compare": "error",
+      "@typescript-eslint/restrict-plus-operands": "error",
+      // '@typescript-eslint/type-annotation-spacing': 'error',
+      "@typescript-eslint/unbound-method": "error",
+    },
+  },
+];

eslint.config.js

@@ -5,7 +5,7 @@ export default defineConfig({
   name,
   entry: ["src/index.ts"],
   format: ["esm"],
-  target: "node20",
+  target: "node24",
   bundle: true,
   splitting: false,
   sourcemap: true,