feat(mobile): learning page fold round 2 — deepen APP-like compression

用户复查后继续压缩(折叠不删减):
- 岗位 SOP:要点默认只显示 2 条,与答案共用「展开全文(含N条要点)」
  开关(原要点全量常显,该面板 1122px 是首因)
- 训练前预习卡:默认只显示「要点」,红线/可说话术收进
  「展开红线与可说话术」(练前场景里预习卡与练页预习视图重复度高)
- 错题本默认 3→2 条(展开全部不变)
- 学习后动作:三个竖排大按钮改为一行三列

高度变化:5452(初始)→3890(第一轮)→3039px(本轮,累计 -44%);
剩余为 8 个功能面板骨架高度,继续压需砍面板,violates 不影响功能原则。
面板分布:错题本 701→544、岗位SOP 1122→738、预习卡 596→361、
学习后动作 234→116。

验证:本地折叠/展开断言全过 + 生产复核 height<3300、双折叠就位。
发布备份 h5-before-$TS。

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

mobile-uni/src/pages/user/learning/index.vue

@@ -117,7 +117,7 @@
           </button>
           <text v-else-if="item.retryAssignmentId" class="mistake-completed">已完成</text>
         </view>
-        <button v-if="visibleMistakes.length > 3" class="fold-toggle" @click="showAllMistakes = !showAllMistakes">
+        <button v-if="visibleMistakes.length > 2" class="fold-toggle" @click="showAllMistakes = !showAllMistakes">
           {{ showAllMistakes ? '收起 ▲' : `展开全部 ${visibleMistakes.length} 条 ▼` }}
         </button>
       </view>
@@ -228,14 +228,14 @@
         </button>
       </view>
       <text v-if="knowledgeResult?.answer" class="answer-text">{{ displayedAnswer }}</text>
-      <button v-if="answerIsLong" class="fold-toggle" @click="showFullAnswer = !showFullAnswer">
-        {{ showFullAnswer ? '收起全文 ▲' : '展开全文 ▼' }}
-      </button>
-      <view v-if="knowledgeResult?.keyPoints?.length" class="keypoints">
-        <text v-for="(point, index) in knowledgeResult.keyPoints" :key="point" class="keypoint">
+      <view v-if="displayedKeyPoints.length" class="keypoints">
+        <text v-for="(point, index) in displayedKeyPoints" :key="point" class="keypoint">
           {{ index + 1 }}. {{ cleanOrderedText(point) }}
         </text>
       </view>
+      <button v-if="sopFoldNeeded" class="fold-toggle" @click="showFullAnswer = !showFullAnswer">
+        {{ showFullAnswer ? '收起全文 ▲' : `展开全文（含 ${knowledgeResult?.keyPoints?.length || 0} 条要点）▼` }}
+      </button>
       <view v-if="knowledgeResult?.snippets?.length" class="snippet-list">
         <view
           v-for="(snippet, index) in knowledgeResult.snippets?.slice(0, 3)"
@@ -265,14 +265,19 @@
           <text class="prep-label">要点</text>
           <text v-for="item in prepCard.keyPoints.slice(0, 3)" :key="`point-${item}`" class="prep-line">{{ item }}</text>
         </view>
-        <view class="prep-block red">
-          <text class="prep-label">红线</text>
-          <text v-for="item in prepCard.redLines.slice(0, 3)" :key="`red-${item}`" class="prep-line">{{ item }}</text>
-        </view>
-        <view class="prep-block script">
-          <text class="prep-label">可说话术</text>
-          <text v-for="item in prepCard.scripts.slice(0, 3)" :key="`script-${item}`" class="prep-line">{{ item }}</text>
-        </view>
+        <template v-if="showPrepDetail">
+          <view class="prep-block red">
+            <text class="prep-label">红线</text>
+            <text v-for="item in prepCard.redLines.slice(0, 3)" :key="`red-${item}`" class="prep-line">{{ item }}</text>
+          </view>
+          <view class="prep-block script">
+            <text class="prep-label">可说话术</text>
+            <text v-for="item in prepCard.scripts.slice(0, 3)" :key="`script-${item}`" class="prep-line">{{ item }}</text>
+          </view>
+        </template>
+        <button class="fold-toggle" @click="showPrepDetail = !showPrepDetail">
+          {{ showPrepDetail ? '收起 ▲' : '展开红线与可说话术 ▼' }}
+        </button>
       </view>
       <view v-else-if="!prepLoading" class="empty">暂无可用预习卡</view>
       <button class="primary-button full-action" @click="goPractice">练一遍</button>
@@ -366,13 +371,21 @@ const ANSWER_PREVIEW_CHARS = 140;
 const showAllMistakes = ref(false);
 const showFullAnswer = ref(false);
 const expandedSnippets = ref<Record<number, boolean>>({});
-const displayedMistakes = computed(() => (showAllMistakes.value ? visibleMistakes.value : visibleMistakes.value.slice(0, 3)));
+const displayedMistakes = computed(() => (showAllMistakes.value ? visibleMistakes.value : visibleMistakes.value.slice(0, 2)));
 const answerIsLong = computed(() => (knowledgeResult.value?.answer || '').length > ANSWER_PREVIEW_CHARS);
 const displayedAnswer = computed(() => {
   const answer = knowledgeResult.value?.answer || '';
   if (showFullAnswer.value || answer.length <= ANSWER_PREVIEW_CHARS) return answer;
   return `${answer.slice(0, ANSWER_PREVIEW_CHARS)}…`;
 });
+const KEYPOINT_PREVIEW_COUNT = 2;
+const displayedKeyPoints = computed(() => {
+  const points = knowledgeResult.value?.keyPoints || [];
+  return showFullAnswer.value ? points : points.slice(0, KEYPOINT_PREVIEW_COUNT);
+});
+const sopFoldNeeded = computed(() =>
+  answerIsLong.value || (knowledgeResult.value?.keyPoints?.length || 0) > KEYPOINT_PREVIEW_COUNT);
+const showPrepDetail = ref(false);
 const toggleSnippet = (index: number) => {
   expandedSnippets.value = { ...expandedSnippets.value, [index]: !expandedSnippets.value[index] };
 };
@@ -1045,11 +1058,17 @@ onUnload(invalidateRequests);
 .snippet-list,
 .action-list {
   display: flex;
-  flex-direction: column;
-  gap: 12px;
+  gap: 10px;
   margin-top: 14px;
 }
 
+.action-list .action-button {
+  flex: 1;
+  min-height: 44px;
+  padding: 0 4px;
+  font-size: 14px;
+}
+
 .task-row {
   display: flex;
   gap: 12px;