feat: add api package

packages/api/src/Domain/Server/User/UserServerInterface.ts

@@ -0,0 +1,6 @@
+import { UserRegistrationRequestParams } from '../../Request/User/UserRegistrationRequestParams'
+import { UserRegistrationResponse } from '../../Response/User/UserRegistrationResponse'
+
+export interface UserServerInterface {
+  register(params: UserRegistrationRequestParams): Promise<UserRegistrationResponse>
+}