added new otp table

migrations/8_totp.sql

@@ -0,0 +1,11 @@
+create table otp (
+	user_id uuid not null,
+	created_at timestamptz not null default current_timestamp,
+	-- enum str on client side
+	otp_method varchar(32) not null,
+	-- 160bit base32-encoded key
+	secret_seed char(32) not null,
+	recovery_key varchar(512) not null,
+	primary key (user_id, otp_method),
+	foreign key (user_id) references users (id) on delete cascade
+);