Add Optional 2FA Support (#61)

* Add TOTP MFA Support

* Add Passkey MFA Support

It's not impossible I missed some minor cleanup, but most things make sense and there isn't a lot of obvious duplication anymore.

---------

Co-authored-by: Bruno Bernardino <me@brunobernardino.com>

lib/utils/multi-factor-auth.ts

@@ -0,0 +1,28 @@
+// This file contains some multi-factor authentication utilities that are isomorphic.
+
+import { MultiFactorAuthMethod, User } from '/lib/types.ts';
+
+export function getMultiFactorAuthMethodsFromUser(
+  user: { extra: Pick<User['extra'], 'multi_factor_auth_methods'> },
+): MultiFactorAuthMethod[] {
+  return user.extra.multi_factor_auth_methods || [];
+}
+
+export function getEnabledMultiFactorAuthMethodsFromUser(
+  user: { extra: Pick<User['extra'], 'multi_factor_auth_methods'> },
+): MultiFactorAuthMethod[] {
+  return getMultiFactorAuthMethodsFromUser(user).filter((method) => method.enabled);
+}
+
+export function getMultiFactorAuthMethodByIdFromUser(
+  user: { extra: Pick<User['extra'], 'multi_factor_auth_methods'> },
+  id: string,
+): MultiFactorAuthMethod | undefined {
+  return getMultiFactorAuthMethodsFromUser(user).find((method) => method.id === id);
+}
+
+export function isMultiFactorAuthEnabledForUser(
+  user: { extra: Pick<User['extra'], 'multi_factor_auth_methods'> },
+): boolean {
+  return getEnabledMultiFactorAuthMethodsFromUser(user).length > 0;
+}