Required `/state` is not implemented

TEP [jetton-offchain-payloads](https://github.com/tonkeeper/TEPs2/blob/cb4be6c2c6d1ae9821b038fe0a8f2b3c0ef999a1/text/0000-jetton-offchain-payloads.md) says:

> 3. **/state**
>
> Returns general information about this API instance.
>
> MUST return a JSON object with...

But current implementation returns 404 NotFound