fix: 修复节点点击无响应 + 支持对比后返回完整导图重新选择复习范围

- MindMapViewer: mind-elixir v5 的 selectNode(el) 不传第二参数导致 selectNewNode 永不触发，改为 monkey-patch selectNode 捕获节点点击
- MindMapViewer: 根节点加入 nodePathMap，子节点路径补全根标题前缀
- ReviewRecall: 新增 resetComparison()，对比完成后可点击「返回完整导图」清空结果，重新选择节点开始新一轮复习

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

src/components/ReviewRecall.vue

@@ -223,6 +223,14 @@ const resetRecall = () => {
   recallTree.value = buildEmptyRecallTree();
 };
 
+// 返回完整标准导图，重新选择复习范围
+const resetComparison = () => {
+  lastResult.value = null;
+  hasCompared.value = false;
+  focusPath.value = "";
+  recallTree.value = buildEmptyRecallTree();
+};
+
 // 编辑标准导图
 const startEditStandard = () => {
   editOutline.value = standard.value?.outline || "";
@@ -438,8 +446,18 @@ onMounted(() => {
     <!-- 标准导图（含对比着色） -->
     <article class="surface-card standard-panel">
       <div class="panel-header">
-        <h3>📖 标准思维导图</h3>
+        <h3>
+          {{ hasCompared ? '📖 标准思维导图（对比结果）' : '📖 标准思维导图' }}
+        </h3>
         <div class="panel-actions">
+          <el-button
+            v-if="hasCompared"
+            size="small"
+            type="success"
+            @click="resetComparison"
+          >
+            返回完整导图
+          </el-button>
           <el-button size="small" @click="standardExpanded = !standardExpanded">
             {{ standardExpanded ? "折叠" : "展开" }}
           </el-button>