post https://api.g.alchemy.com/signer/v1/whoami
Authenticates a user and returns their identity and account information, enabling the application to grant the user access to their Embedded Account functionalities. This endpoint is used to confirm user authentication via email or passkey, thereby authorizing them to perform actions as the owner of a smart account or to conduct transactions as an EOA signer. It ensures that only authenticated users can access and manage their accounts.