fix(排名): 老师点「本班」不再随手挑个交题最多的班，改成布置过作业的班、上次选的班，都没有就停在全部

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

apps/web/src/utils/constants.ts

@@ -157,6 +157,7 @@ export const STORAGE_KEY = {
   ADMIN_SIDER_COLLAPSED: "adminSiderCollapsed",
   DEMO_MODE: "demoMode",
   LOGIN_CLASS: "loginClass",
+  RANK_CLASS: "rankClass",
 }
 
 export const DIFFICULTY = {