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/MindMapViewer.vue

@@ -99,11 +99,26 @@ const toElixirNode = (node: MindMapTreeNode, ancestors: string[] = []): any => {
 
 const toElixirData = (tree: MindMapTreeNode): MindElixirData => {
   nodeCounter = 0;
+  const rootTitle = tree.title || "思维导图";
+  // register root node in path map so clicking it also works
+  if (props.selectable) {
+    nodePathMap["root"] = {
+      title: rootTitle,
+      path: rootTitle,
+      childCount: (tree.children || []).reduce(
+        (sum, c) => sum + 1 + countAllDescendants(c),
+        0,
+      ),
+    };
+  }
   return {
     nodeData: {
       id: "root",
-      topic: tree.title || "思维导图",
-      children: (tree.children || []).map(c => toElixirNode(c)),
+      topic: rootTitle,
+      // pass root title as ancestor so child paths include it (e.g. "根 / 子节点")
+      children: (tree.children || []).map((c) =>
+        toElixirNode(c, [rootTitle]),
+      ),
     },
   } as MindElixirData;
 };
@@ -147,18 +162,31 @@ const render = () => {
     });
   }
 
-  instance.bus.addListener("selectNewNode", (node: any) => {
-    if (props.selectable && node?.id) {
-      const info = nodePathMap[node.id];
+  // mind-elixir v5: selectNode(el) is called on every node click, but the
+  // selectNewNode event is never fired (it requires selectNode(el, true),
+  // which the default click handler never passes). Monkey-patch selectNode
+  // to hook into node clicks for both selectable and source-navigation modes.
+  const origSelectNode = instance.selectNode.bind(instance);
+  instance.selectNode = function (el: any, fireEvent?: boolean) {
+    origSelectNode(el, fireEvent);
+    if (!el?.nodeObj) return;
+    const nodeData = el.nodeObj;
+    // selectable mode → emit node-select with title/path/childCount
+    if (props.selectable && nodeData?.id) {
+      const info = nodePathMap[nodeData.id];
       if (info) {
         emit("node-select", info);
         return;
       }
     }
-    if (node?.sourceType && node?.sourceId != null) {
-      emit("node-click", { sourceType: String(node.sourceType), sourceId: Number(node.sourceId) });
+    // source navigation → emit node-click with sourceType/sourceId
+    if (nodeData?.sourceType && nodeData?.sourceId != null) {
+      emit("node-click", {
+        sourceType: String(nodeData.sourceType),
+        sourceId: Number(nodeData.sourceId),
+      });
     }
-  });
+  };
 };
 
 watch(