fix: resolve ESLint errors

- Use node: prefix for built-in modules (assert, fs, child_process)
- Remove structuredClone availability check (always available in Node.js 20+)
- Add Buffer and structuredClone to ESLint globals
- Fix quote style consistency
- All ESLint checks now pass

Author: kamio90

.eslintrc.js

@@ -10,6 +10,8 @@ module.exports = {
   },
   globals: {
     process: 'readonly',
+    Buffer: 'readonly',
+    structuredClone: 'readonly',
   },
   rules: {
     'no-extend-native': [ 'error', { exceptions: [ 'Array' ] } ],