feat(智能分析): 解题表格改服务端分页，/ai/detail 不再下发整份 solved

原来 /ai/detail 把区间内做出来的每道题连排名带等级整份下发，一个活跃学生一年几百道，
一次请求就是几百 KB，而表格一屏只看得到二十行。

拆成两支：
- GET /ai/detail 只留聚合（solvedCount、difficulty、tags、attempts、activity、errors…）
- GET /ai/solved?offset&limit 按首次通过时间升序分页给逐题明细

排名只跟当前这批题有关，所以分页那支只算一页的 problemIds，不必把整年算一遍。抽出
firstAcQuery / buildSolved / listSolved 三个函数，detail 和分页两边共用。

前端相应改动：
- 难度分布改读后端的 difficulty 聚合（本来就在下发，之前是从逐题列表里现数的）
- 几次做对改读新的 attempts 数组（每道题的尝试次数）；tooltip 里的题名去掉了 ——
  明细是分页拿的，不该为了一个 tooltip 把全量拉回来
- Overview 用 solvedCount
- SolvedTable 的代码提交那张走 remote 分页，流程图那张仍是本地分页（一个 OJ 的
  流程图题就那么几道，全量下发没问题）；换时间范围回到第一页
- 表格原来是 max-height 1500 的滚动区，现在由分页兜住，滚动条和分页器不再并存

/ai/analysis 的 prompt 仍然带逐题明细（少了它模型只剩聚合数字），但顺手卡了 200 条 ——
以前是整份 solved 无上限塞进去，题做得多的学生一次调用能顶好几倍 token。

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01LZuPwqDmLEiK9zgQ9z9sVn

apps/web/src/oj/store/ai.ts

@@ -1,10 +1,11 @@
-import type { DetailsData, DurationData } from "utils/types"
+import type { DetailsData, DurationData, SolvedProblem } from "utils/types"
 import { aiStreamError, consumeJSONEventStream } from "utils/stream"
 import {
   getAIDetailData,
   getAIDurationData,
   getAIHeatmapData,
   getAIPinnedReport,
+  getAISolved,
 } from "../api"
 
 export const useAIStore = defineStore("ai", () => {
@@ -23,7 +24,8 @@ export const useAIStore = defineStore("ai", () => {
     tags: {},
     difficulty: {},
     contestCount: 0,
-    solved: [],
+    solvedCount: 0,
+    attempts: [],
     flowcharts: [],
     activity: [],
     errors: [],
@@ -31,10 +33,17 @@ export const useAIStore = defineStore("ai", () => {
   })
   const heatmapData = ref<{ timestamp: number; value: number }[]>([])
 
+  // 解题明细走服务端分页：一个活跃学生一年几百道题，整份跟着 detail 一起下发没必要
+  const solvedRows = ref<SolvedProblem[]>([])
+  const solvedTotal = ref(0)
+  const solvedPage = ref(1)
+  const solvedPageSize = ref(20)
+
   const loading = reactive({
     fetching: false, // 合并 details 和 duration 的 loading
     ai: false,
     heatmap: false,
+    solved: false,
   })
 
   const mdContent = ref("")
@@ -48,12 +57,13 @@ export const useAIStore = defineStore("ai", () => {
     )
     detailsData.start = res.start
     detailsData.end = res.end
-    detailsData.solved = res.solved
     detailsData.grade = res.grade
     detailsData.className = res.className
     detailsData.tags = res.tags
     detailsData.difficulty = res.difficulty
     detailsData.contestCount = res.contestCount
+    detailsData.solvedCount = res.solvedCount
+    detailsData.attempts = res.attempts
     detailsData.activity = res.activity
     detailsData.errors = res.errors
     detailsData.rankScope = res.rankScope
@@ -69,6 +79,25 @@ export const useAIStore = defineStore("ai", () => {
     durationData.value = res
   }
 
+  async function fetchSolved(page = solvedPage.value) {
+    if (!rangeStart.value || !rangeEnd.value) return
+    loading.solved = true
+    try {
+      const res = await getAISolved(
+        rangeStart.value,
+        rangeEnd.value,
+        (page - 1) * solvedPageSize.value,
+        solvedPageSize.value,
+        targetUsername.value || undefined,
+      )
+      solvedRows.value = res.results
+      solvedTotal.value = res.total
+      solvedPage.value = page
+    } finally {
+      loading.solved = false
+    }
+  }
+
   async function fetchHeatmapData() {
     loading.heatmap = true
     const res = await getAIHeatmapData(targetUsername.value || undefined)
@@ -83,11 +112,14 @@ export const useAIStore = defineStore("ai", () => {
   ) {
     rangeStart.value = start
     rangeEnd.value = end
+    // 换时间范围就回到第一页，否则停在第 5 页但新范围只有两页
+    solvedPage.value = 1
     loading.fetching = true
     try {
       await Promise.all([
         fetchDetailsData(start, end),
         fetchDurationData(end, duration),
+        fetchSolved(1),
       ])
     } finally {
       loading.fetching = false
@@ -196,6 +228,11 @@ export const useAIStore = defineStore("ai", () => {
   return {
     fetchAnalysisData,
     fetchHeatmapData,
+    fetchSolved,
+    solvedRows,
+    solvedTotal,
+    solvedPage,
+    solvedPageSize,
     fetchAIAnalysis,
     fetchPinnedReport,
     simulatePinnedStream,