feat: add teaching enhancement features

1. AI personalized hints after 3 failures (streaming SSE)
2. Submission error distribution panel in "my submissions" tab
3. Similar problem recommendations on AC or 3+ failures
4. Admin stuck problems analysis page

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/oj/problem/components/SubmissionResult.vue

@@ -3,11 +3,24 @@ import { JUDGE_STATUS, SubmissionStatus } from "utils/constants"
 import { submissionMemoryFormat, submissionTimeFormat } from "utils/functions"
 import type { Submission } from "utils/types"
 import SubmissionResultTag from "shared/components/SubmissionResultTag.vue"
+import { useProblemStore } from "oj/store/problem"
+import { consumeJSONEventStream } from "utils/stream"
+import { MdPreview } from "md-editor-v3"
+import "md-editor-v3/lib/preview.css"
+import { useDark } from "@vueuse/core"
 
 const props = defineProps<{
   submission?: Submission
 }>()
 
+const isDark = useDark()
+const problemStore = useProblemStore()
+
+// AI 提示状态
+const hintContent = ref("")
+const hintLoading = ref(false)
+const hintError = ref("")
+
 // 错误信息格式化
 const msg = computed(() => {
   if (!props.submission) return ""
@@ -30,6 +43,50 @@ const msg = computed(() => {
   return msg
 })
 
+// 是否显示AI提示区域
+const showAIHint = computed(() => {
+  if (!props.submission) return false
+  return (
+    problemStore.totalFailCount >= 3 &&
+    props.submission.result !== SubmissionStatus.accepted &&
+    props.submission.result !== SubmissionStatus.pending &&
+    props.submission.result !== SubmissionStatus.judging &&
+    props.submission.result !== SubmissionStatus.submitting
+  )
+})
+
+async function fetchHint(submissionId: string) {
+  hintLoading.value = true
+  hintContent.value = ""
+  hintError.value = ""
+
+  try {
+    const response = await fetch("/api/ai/hint", {
+      method: "POST",
+      headers: { "Content-Type": "application/json" },
+      body: JSON.stringify({ submission_id: submissionId }),
+    })
+
+    await consumeJSONEventStream(response, {
+      onMessage: (data: {
+        type: string
+        content?: string
+        message?: string
+      }) => {
+        if (data.type === "delta" && data.content) {
+          hintContent.value += data.content
+        } else if (data.type === "error") {
+          hintError.value = data.message || "AI 提示生成失败"
+        }
+      },
+    })
+  } catch (e: any) {
+    hintError.value = e.message || "请求失败"
+  } finally {
+    hintLoading.value = false
+  }
+}
+
 // 测试用例表格数据（只在部分通过时显示）
 const infoTable = computed(() => {
   if (!props.submission?.info?.data?.length) return []
@@ -87,6 +144,36 @@ const columns: DataTableColumn<Submission["info"]["data"][number]>[] = [
         :columns="columns"
       />
     </n-flex>
+
+    <!-- AI 提示区域 -->
+    <template v-if="showAIHint">
+      <n-divider />
+      <n-card size="small">
+        <template #header>
+          <span class="gradient-text">AI 提示</span>
+        </template>
+        <n-alert
+          v-if="hintError"
+          type="error"
+          :title="hintError"
+          class="mb-3"
+        />
+        <n-button
+          v-if="!hintContent && !hintLoading"
+          type="primary"
+          @click="fetchHint(submission.id)"
+        >
+          让 AI 分析我的代码
+        </n-button>
+        <n-spin v-else-if="hintLoading && !hintContent" size="small" />
+        <MdPreview
+          v-if="hintContent"
+          :model-value="hintContent"
+          preview-theme="vuepress"
+          :theme="isDark ? 'dark' : 'light'"
+        />
+      </n-card>
+    </template>
   </div>
 </template>
 
@@ -96,4 +183,12 @@ const columns: DataTableColumn<Submission["info"]["data"][number]>[] = [
   word-break: break-all;
   line-height: 1.5;
 }
+
+.gradient-text {
+  background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
+  -webkit-background-clip: text;
+  -webkit-text-fill-color: transparent;
+  background-clip: text;
+  font-weight: bold;
+}
 </style>