feat: add functional authentication

spec/schemas/contact.ts

@@ -0,0 +1,9 @@
+import z from "zod";
+
+import { EmailSchema } from "./email.ts";
+
+export const ContactSchema = z.object({
+  emails: z.array(EmailSchema).default([]).describe("A list of email addresses associated with the contact."),
+});
+
+export type Contact = z.infer<typeof ContactSchema>;