Returns the full profile of the user associated with the current session.

For User sessions (created with a customerUid), this returns the profile of that specific customer.

For System sessions (no customerUid), this returns the profile of the organization's root system user.

Use this endpoint to:

• Fetch customer details such as name, email, phone, date of birth,
  and physical addresses after creating a user-scoped session.

• Confirm session identity — verify which user the current session
  is acting on behalf of before performing sensitive operations.