feat(前台): 各页直达后台对应功能——编辑这一课、新建比赛、编辑这条公告……

题目页「编辑题目」从只给超管放宽到有权改这道题的人（含学生管理员改自己出的题）；
题目、比赛、题单列表加「新建」；自学首页加「自学情况」「管理教程」，课文加「编辑这一课」；
公告加「编辑这条」「发公告」；成就加「管理成就」；智能分析加「AI 报告」，看某个学生时
带着用户名过去直接筛到他。按钮统一走 shared/components/AdminLink.vue。

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

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

@@ -9,6 +9,8 @@ import ContestTitle from "shared/components/ContestTitle.vue"
 import Pagination from "shared/components/Pagination.vue"
 import { useAuthModalStore } from "shared/store/authModal"
 import { usePagination } from "shared/composables/pagination"
+import AdminLink from "shared/components/AdminLink.vue"
+import { useBreakpoints } from "shared/composables/breakpoints"
 import { useUserStore } from "shared/store/user"
 import { ContestStatus } from "utils/constants"
 import ContestBadge from "./components/ContestBadge.vue"
@@ -19,6 +21,7 @@ import ContestBadge from "./components/ContestBadge.vue"
  */
 const router = useRouter()
 const userStore = useUserStore()
+const { isDesktop } = useBreakpoints()
 const authStore = useAuthModalStore()
 const theme = useThemeVars()
 const tone = useTone()
@@ -145,6 +148,10 @@ const warning = computed(() => tone("warning"))
         {{ item.label }}
       </button>
       <n-input v-model:value="query.keyword" clearable placeholder="比赛名" style="width: 200px" />
+      <!-- 手机上一行放不下，也没人在手机上出题，只给电脑 -->
+      <AdminLink v-if="isDesktop && userStore.isTeacherOrAbove" to="/admin/contest/create"
+        >新建比赛</AdminLink
+      >
     </div>
 
     <div