add initial endpoints

identity/migrations/20240115015514_init.sql

@@ -17,6 +17,7 @@ create type instance_status as enum ('active', 'suspended');
 create table chat_instances (
     id         text primary key,
     domain     text not null unique,
+    base_url   text not null,
     public_key text not null,
     status     instance_status not null default 'active',
     reason     text