[`StateAndPropsTransformer`](https://github.com/mayu-live/framework/blob/main/lib/mayu/resources/transformers/haml.rb#L873) transformes `$foo` to `self.props[:foo]`. Would be convenient to have the same thing for state. Not 100% sure how it should work with `update { |state| }`.. could probably figure out something clever... or maybe use [mayu-signals](https://github.com/mayu-live/signals)