[Enhance] Limited custom banner

- For Arcaea 6.5.0
- Add limited support for custom banners. It will be improved in the future.  #202

latest version/database/init/tables.sql

@@ -37,7 +37,8 @@ world_mode_locked_end_ts int,
 beyond_boost_gauge real default 0,
 kanae_stored_prog real default 0,
 mp_notification_enabled int default 1,
-insight_state default 4  -- 这里写 4 是为了避免不能切换状态和无故被侵入
+insight_state default 4,  -- 这里写 4 是为了避免不能切换状态和无故被侵入
+custom_banner text
 );
 create table if not exists login(access_token text,
 user_id int,