feat(web): 教师顶栏的求助列表

按题目分组，同题多人时标出人数。按等待时长排序但不强制先来先到 ——
上课时有的问题一句话说清、有的要讲五分钟。

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01K1d8B3f4SXJwDvUY625eQd

apps/web/src/shared/components/Header.vue

@@ -6,6 +6,7 @@ import { useLearnProgress } from "shared/composables/learnProgress"
 import { useAuthModalStore } from "shared/store/authModal"
 import { useScreenModeStore } from "shared/store/screenMode"
 import { logout } from "../api"
+import HelpRequestList from "./HelpRequestList.vue"
 import { useConfigStore } from "../store/config"
 import { useUserStore } from "../store/user"
 import { trickOrTreat } from "utils/functions"
@@ -328,6 +329,7 @@ function handleMenuSelect(key: string) {
       >
         {{ screenMode }}
       </n-button>
+      <HelpRequestList v-if="isDesktop && userStore.isTeacherOrAbove" />
       <div v-if="userStore.isFinished">
         <n-dropdown v-if="userStore.isAuthed" :options="options" size="large">
           <n-button>

apps/web/src/shared/components/HelpRequestList.vue

@@ -0,0 +1,98 @@
+<script setup lang="ts">
+import { Icon } from "@iconify/vue"
+import { useCollabStore } from "shared/store/collab"
+
+const collabStore = useCollabStore()
+
+// 等待时长要每秒走一格，所以自己转一个 now
+const now = ref(Date.now())
+let timer: number | null = null
+onMounted(() => {
+  timer = window.setInterval(() => (now.value = Date.now()), 1000)
+})
+onUnmounted(() => {
+  if (timer !== null) window.clearInterval(timer)
+})
+
+const waited = (createdAt: number) => {
+  const seconds = Math.max(0, Math.floor((now.value - createdAt) / 1000))
+  const m = Math.floor(seconds / 60)
+  const s = seconds % 60
+  return `${m}:${String(s).padStart(2, "0")}`
+}
+
+const handleAccept = (studentId: number, status: string) => {
+  // 已被别的老师接走的不能点
+  if (status === "active") return
+  collabStore.accept(studentId)
+}
+</script>
+
+<template>
+  <n-popover trigger="click" placement="bottom-end" style="padding: 0">
+    <template #trigger>
+      <n-badge :value="collabStore.pendingCount" :max="99">
+        <n-button>
+          <Icon icon="fluent-emoji:raising-hand" height="20" />
+          <span style="padding-left: 8px">求助</span>
+        </n-button>
+      </n-badge>
+    </template>
+
+    <div style="width: 320px; max-height: 60vh; overflow: auto; padding: 8px">
+      <n-empty v-if="collabStore.groupedRequests.length === 0" description="暂无求助" />
+
+      <div v-for="group in collabStore.groupedRequests" :key="group.problemId">
+        <!-- 同题多人是个教学信号：该停下来全班讲，而不是挨个救 -->
+        <n-flex align="center" justify="space-between" style="padding: 6px 4px">
+          <n-text depth="3" style="font-size: 12px">
+            {{ group.problemId }} · {{ group.problemTitle }}
+          </n-text>
+          <n-tag v-if="group.items.length > 1" size="small" type="warning">
+            {{ group.items.length }} 人
+          </n-tag>
+        </n-flex>
+
+        <n-flex
+          v-for="item in group.items"
+          :key="item.studentId"
+          align="center"
+          justify="space-between"
+          :style="{
+            padding: '6px 8px',
+            borderRadius: '4px',
+            opacity: item.status === 'active' ? 0.5 : 1,
+            cursor: item.status === 'active' ? 'default' : 'pointer',
+          }"
+          @click="handleAccept(item.studentId, item.status)"
+        >
+          <n-flex vertical :size="2">
+            <n-text>
+              {{ item.studentName }}
+              <n-text depth="3" v-if="item.className">（{{ item.className }}）</n-text>
+            </n-text>
+            <n-text depth="3" style="font-size: 12px">
+              {{
+                item.status === "active"
+                  ? `${item.teacherName} 处理中`
+                  : `等了 ${waited(item.createdAt)}`
+              }}
+            </n-text>
+          </n-flex>
+
+          <n-button
+            v-if="item.status === 'pending'"
+            quaternary
+            circle
+            size="small"
+            @click.stop="collabStore.reject(item.studentId)"
+          >
+            <Icon icon="mdi:close" height="16" />
+          </n-button>
+        </n-flex>
+
+        <n-divider style="margin: 4px 0" />
+      </div>
+    </div>
+  </n-popover>
+</template>