fix(bookDetail): 优化书籍详情页简介展开折叠检测逻辑

改用ResizeObserver替代原有的setTimeout与hasEllipsis检测方式，实现更精准的文本溢出判断；添加书籍简介内容变化监听，同步更新展开状态；在组件失活与卸载时正确清理观察者与动画帧计时器。

@@ -16,7 +16,7 @@
       </div>
       <div class="book-intro">
         <p class="book-post">{{ bookInfo.name }}</p>
-        <div id="book-intro" :class="{ 'van-multi-ellipsis--l3': isToggle }" v-html="bookInfo.note"></div>
+        <div id="book-intro" ref="bookIntroRef" :class="{ 'van-multi-ellipsis--l3': isToggle }" v-html="bookInfo.note"></div>
         <template v-if="hasToggle">
           <div v-if="isToggle" class="book-toggle-icon" @click="isToggle = false">
             展开&nbsp;
@@ -121,9 +121,9 @@
 </template>
 
 <script setup>
-import { ref, onActivated, onMounted } from 'vue'
+import { ref, watch, nextTick, onActivated, onMounted, onDeactivated, onBeforeUnmount } from 'vue'
 import { useRoute, useRouter, onBeforeRouteLeave } from 'vue-router'
-import { _, storeToRefs, mainStore, showSuccessToast, hasEllipsis } from '@/utils/generatePackage'
+import { _, storeToRefs, mainStore, showSuccessToast } from '@/utils/generatePackage'
 import { MyButton, VideoCard, NoticeOverlayModule, DonateFlower, ShortcutFixed } from '@/utils/generateModules'
 import { icon_video, icon_up, icon_down, icon_subscribed, icon_unsubscribe, no_image } from '@/utils/generateIcons'
 import { JSJ_FORM_MANDARIN, JSJ_FORM_LOCALISM } from '@/constant'
@@ -157,13 +157,76 @@ const customStyle = ref({
 })
 
 const donateInfo = ref({})
+const bookIntroRef = ref(null)
+
+const hasToggle = ref(false); // 判断是否有展开文字，默认没有
+const isToggle = ref(true); // 判断展开状态，默认展开
+
+let introResizeObserver = null
+let introMeasureTimer = null
+
+const getIntroToggleStatus = () => {
+  const el = bookIntroRef.value;
+  if (!el || !el.clientWidth) {
+    return false;
+  }
+
+  const clone = el.cloneNode(true);
+  clone.removeAttribute('id');
+  clone.style.position = 'fixed';
+  clone.style.left = '-99999px';
+  clone.style.top = '-99999px';
+  clone.style.zIndex = '-1';
+  clone.style.visibility = 'hidden';
+  clone.style.pointerEvents = 'none';
+  clone.style.height = 'auto';
+  clone.style.maxHeight = 'none';
+  clone.style.width = `${el.clientWidth}px`;
+  clone.classList.add('van-multi-ellipsis--l3');
+
+  document.body.appendChild(clone);
+  const flag = clone.scrollHeight > clone.clientHeight;
+  document.body.removeChild(clone);
+
+  return flag;
+}
+
+const updateHasToggle = async () => {
+  await nextTick();
+  if (introMeasureTimer) {
+    cancelAnimationFrame(introMeasureTimer);
+  }
+  introMeasureTimer = requestAnimationFrame(() => {
+    hasToggle.value = getIntroToggleStatus();
+  });
+}
+
+const bindIntroObserver = () => {
+  if (!window.ResizeObserver || introResizeObserver || !bookIntroRef.value) return;
+
+  introResizeObserver = new ResizeObserver(() => {
+    updateHasToggle();
+  });
+  introResizeObserver.observe(bookIntroRef.value);
+}
+
+const clearIntroObserver = () => {
+  if (introResizeObserver) {
+    introResizeObserver.disconnect();
+    introResizeObserver = null;
+  }
+
+  if (introMeasureTimer) {
+    cancelAnimationFrame(introMeasureTimer);
+    introMeasureTimer = null;
+  }
+}
+
 onMounted(async () => {
   const { data } = await prepareDonateAPI();
   donateInfo.value = data;
-  setTimeout(() => {
-    // 判断是否显示简介的展开图标
-    hasToggle.value = hasEllipsis(`book-intro`);
-  }, 500);
+  bindIntroObserver();
+  updateHasToggle();
   // TAG: 监听滚动到底部
   // 快捷访问组件高度动态调整
   // window.onscroll = function () {
@@ -202,9 +265,10 @@ window.onscroll = function () {
   }
 }
 
-// 判断是否显示简介的展开图标
-const hasToggle = ref(false); // 判断是否有展开文字，默认没有
-const isToggle = ref(true); // 判断展开状态，默认展开
+watch(() => bookInfo.value?.note, () => {
+  isToggle.value = true;
+  updateHasToggle();
+});
 
 /**
  * 书籍订阅
@@ -327,6 +391,16 @@ onActivated(() => { // keepAlive 重置后执行回调
   // 更新是否实名认证和儿童信息
   const data = useDefaultPerf($route.query.id);
   userInfo = data.userInfo;
+  bindIntroObserver();
+  updateHasToggle();
+});
+
+onDeactivated(() => {
+  clearIntroObserver();
+});
+
+onBeforeUnmount(() => {
+  clearIntroObserver();
 });
 
 onBeforeRouteLeave(() => {