Verify each finding against the current code and only fix it if needed.

Outside diff comments:
In `@crates/napi/src/bindgen_runtime/iterator.rs`:
- Around line 255-306: The current code calls Object.setPrototypeOf(class_proto,
iterator_proto) which flattens the prototype chain and discards any intermediate
base prototypes; instead, walk the prototype chain starting at class_proto using
repeated napi_get_prototype and napi_strict_equals (the same checks used for
class_proto_parent/already_inherits_iterator) to find the highest prototype
whose parent is not Iterator.prototype, then call Object.setPrototypeOf on that
prototype to set its parent to iterator_proto (preserving existing links);
update the argv/ni_get_named_property/Object.setPrototypeOf usage so the
setPrototypeOf call targets the identified prototype rather than class_proto,
ensuring generator classes keep their own methods while inheriting
Iterator.prototype.

---

Nitpick comments:
In `@examples/napi/__tests__/generator.spec.ts`:
- Around line 104-117: Add a derived-class regression test by defining class
Child extends Fib4 and instantiating it (e.g., const child = new Child(0,1));
assert that Object.getPrototypeOf(child) === Child.prototype,
Object.getPrototypeOf(Child.prototype) === Fib4.prototype and
Object.getPrototypeOf(Fib4.prototype) === Iterator.prototype (when Iterator
exists); also assert typeof child.toJSON === 'function' and child.toJSON()
returns the same array (and JSON.stringify(child) matches), and that iterator
helpers like child.map are available — this ensures Child.prototype and
Fib4.prototype remain in the chain and toJSON still resolves from
Fib4.prototype.