chore: 将前端移动到 client/ 目录，准备合并为单仓库

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

client/src/components/task/ChallengeList.vue

@@ -0,0 +1,83 @@
+<template>
+  <div class="container" v-if="taskTab === TASK_TYPE.Challenge">
+    <n-empty v-if="!challenges.length">暂无挑战，敬请期待</n-empty>
+    <n-flex v-else vertical :size="12">
+      <n-card
+        v-for="item in challenges"
+        :key="item.display"
+        hoverable
+        :class="['challenge-card', { submitted: item.submitted }]"
+        @click="select(item)"
+      >
+        <template #header>
+          <n-flex align="center" :size="6">
+            <span v-if="item.submitted" class="check-icon">✓</span>
+            <span :class="{ 'submitted-title': item.submitted }">{{
+              item.title
+            }}</span>
+          </n-flex>
+        </template>
+        <template #header-extra>
+          <n-flex :size="6">
+            <n-tag type="warning" size="small">{{ item.score }} 分</n-tag>
+            <n-tag v-if="item.pass_score != null" size="small"
+              >及格 {{ item.pass_score }} 分</n-tag
+            >
+          </n-flex>
+        </template>
+        <n-text depth="3" class="challenge-author">
+          出题人：{{ item.author_name || "未设置" }}
+        </n-text>
+      </n-card>
+    </n-flex>
+  </div>
+</template>
+<script setup lang="ts">
+import { ref, onMounted } from "vue"
+import { useRouter } from "vue-router"
+import { Challenge } from "../../api"
+import { taskTab } from "../../store/task"
+import { TASK_TYPE } from "../../utils/const"
+import type { ChallengeSlim } from "../../utils/type"
+
+const router = useRouter()
+const challenges = ref<ChallengeSlim[]>([])
+
+function select(item: ChallengeSlim) {
+  router.push({ name: "home-challenge", params: { display: item.display } })
+}
+
+onMounted(async () => {
+  challenges.value = await Challenge.listDisplay()
+})
+</script>
+<style scoped>
+.container {
+  padding: 16px;
+  overflow: auto;
+}
+
+.challenge-card {
+  cursor: pointer;
+}
+
+.challenge-card.submitted {
+  background-color: #f6ffed;
+  border-color: #b7eb8f;
+}
+
+.check-icon {
+  color: #52c41a;
+  font-size: 14px;
+  font-weight: bold;
+}
+
+.submitted-title {
+  color: #888;
+}
+
+.challenge-author {
+  display: block;
+  font-size: 13px;
+}
+</style>