Expose whoami

[ivpusic]

Exposing WhoAmI function via Golang sdk

[cursor]

PR Summary

Low Risk
Low risk additive change that introduces a new WhoAmI API call and response model without altering existing request/response flows.

Overview
Adds a new WhoAmI() method to the public DuneClient interface and implements it on duneClient, calling the /api/whoami endpoint to return the identity tied to the current API key.

Introduces a models.WhoAmIResponse struct and wires in a new whoamiURLTemplate constant to support the request.

^{Written by Cursor Bugbot for commit 01557f6. Configure here.}

[TheEdgeOfRage]

We generally don't want to expose user/team IDs. What would be the usecase here? We have a way to convert IDs to handles using core. You can make a call to that API to return the handle instead