revert(提交列表): 撤掉班级下拉里补「近半年有提交的班」那一版，下拉回到只用系统设定的班级列表

改成在右栏名字旁加「只看这个班」过滤按钮（下一条）。
This reverts commit 61ec7d7.

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

apps/web/src/oj/api.ts

@@ -167,11 +167,6 @@ export function getTodaySubmissionCount(language?: string) {
   return api.get<number>("submissions/today-count", { params: { language } })
 }
 
-/** 近半年有提交的班级（老师用），补上网站配置里已经摘掉的班 */
-export function getSubmissionClasses() {
-  return api.get<string[]>("submissions/classes")
-}
-
 /** 「今日提交数」标签点开的统计。公开接口，口径同那颗标签：今天 + 非比赛提交 */
 export function getTodaySubmissionStatistics() {
   return api.get<TodaySubmissionStatistics>("submissions/today-statistics")

apps/web/src/oj/submission/list.vue

@@ -7,7 +7,6 @@ import {
   adminRejudge,
   getClassLesson,
   getFlowchartSubmissions,
-  getSubmissionClasses,
   getSubmissions,
   getTodaySubmissionCount,
   retryFlowchartSubmission,
@@ -445,33 +444,11 @@ const languageOptions = [
   { label: "SQL", value: "SQL" },
 ]
 
-// 配置里的班级列表是「注册时能选的班」，摘掉的老班还在交，得从提交里补出来
-const activeClasses = ref<string[]>([])
-watch(
-  teacher,
-  async (isTeacher) => {
-    if (!isTeacher || activeClasses.value.length) return
-    try {
-      activeClasses.value = await getSubmissionClasses()
-    } catch {
-      // 补不上就只有配置里那些，不打扰
-    }
-  },
-  { immediate: true },
-)
-
 const classOptions = computed(() => {
   const list = configStore.config?.classList ?? []
-  const others = activeClasses.value.filter((item) => !list.includes(item)).reverse()
-  // 带进来的班级哪边都没有（手打的）也要显示得出来，不然框里是空的却在筛
-  if (query.className && !list.includes(query.className) && !others.includes(query.className))
-    others.unshift(query.className)
-  const option = (item: string) => ({ label: classLabel(item), value: item })
-  if (!others.length) return list.map(option)
-  return [
-    { type: "group", label: "班级列表", key: "listed", children: list.map(option) },
-    { type: "group", label: "不在班级列表里", key: "others", children: others.map(option) },
-  ]
+  // 带进来的班级不在配置里（老班、手打的）也要显示得出来，不然框里是空的却在筛
+  const all = query.className && !list.includes(query.className) ? [query.className, ...list] : list
+  return all.map((item) => ({ label: classLabel(item), value: item }))
 })
 
 const contestProblemOptions = computed(() => [