Add self-service account management commands (delete, update username/email/password/profile)

web/backend/Features/Features.Auth/Commands/UpdateEmail/UpdateEmailCommand.cs

@@ -0,0 +1,14 @@
+using Features.Auth.Dtos;
+using MediatR;
+
+namespace Features.Auth.Commands.UpdateEmail;
+
+/// <summary>
+///     Changes the email address of the given user account. The account's <c>EmailConfirmed</c> status
+///     is reset to unconfirmed as a result.
+/// </summary>
+/// <param name="UserAccountId">
+///     The authenticated caller's own ID, extracted from the access token -- never bind this from
+///     client-supplied input.
+/// </param>
+public record UpdateEmailCommand(Guid UserAccountId, string NewEmail) : IRequest<UpdateEmailPayload>;