fix: 树状视图展开文件夹为空 - 递归拍平渲染

原模板只遍历 treeData 根级节点, 从不渲染 node.children, 导致展开后为空。
改为 flattenedTree computed 将树拍平为列表:
- 只包含已展开文件夹的子节点
- 每项带 level 用于缩进 (paddingLeft)
- 文件夹和叶子节点在列表中按正确顺序排列
- 叶子节点支持 active/selected 高亮和右键菜单

src/renderer/src/components/KeyList.vue

@@ -474,6 +474,27 @@ function isFolderExpanded(path: string): boolean {
   return expandedFolders.value.has(path)
 }
 
+interface FlatTreeNode {
+  node: TreeNode
+  level: number
+  expanded: boolean
+}
+
+const flattenedTree = computed<FlatTreeNode[]>(() => {
+  const result: FlatTreeNode[] = []
+  function walk(nodes: TreeNode[], level: number) {
+    for (const node of nodes) {
+      const expanded = isFolderExpanded(node.fullPath)
+      result.push({ node, level, expanded })
+      if (!node.isLeaf && expanded) {
+        walk(node.children, level + 1)
+      }
+    }
+  }
+  walk(treeData.value, 0)
+  return result
+})
+
 function isKeySelected(keyName: string): boolean {
   return keyStore.selectedKey === keyName && !multiSelect.value
 }
@@ -674,30 +695,32 @@ onUnmounted(() => {
 
       <!-- Tree View -->
       <div v-else class="key-tree">
-        <template v-for="node in treeData" :key="node.fullPath">
+        <template v-for="item in flattenedTree" :key="item.node.fullPath">
           <!-- Folder -->
           <div
-            v-if="!node.isLeaf"
+            v-if="!item.node.isLeaf"
             class="tree-item folder-item"
-            @click="toggleFolder(node.fullPath)"
+            :style="{ paddingLeft: `${12 + item.level * 16}px` }"
+            @click="toggleFolder(item.node.fullPath)"
           >
-            <el-icon class="tree-arrow" :class="{ expanded: isFolderExpanded(node.fullPath) }">
+            <el-icon class="tree-arrow" :class="{ expanded: item.expanded }">
               <ArrowRight />
             </el-icon>
             <el-icon class="tree-icon folder-icon"><Folder /></el-icon>
-            <span class="tree-name">{{ formatKeyName(node.name) }}</span>
-            <span class="tree-count">{{ node.count }}</span>
+            <span class="tree-name">{{ formatKeyName(item.node.name) }}</span>
+            <span class="tree-count">{{ item.node.count }}</span>
           </div>
-          <div v-else class="tree-children" :class="{ hidden: !isFolderExpanded(node.fullPath) }">
-            <div
-              class="tree-item leaf-item"
-              @click="selectKey(node.fullPath, $event)"
-              @contextmenu.prevent="onKeyContextMenu($event, node.fullPath)"
-            >
-              <span class="tree-spacer"></span>
-              <el-icon class="tree-icon"><Document /></el-icon>
-              <span class="tree-name">{{ formatKeyName(node.name) }}</span>
-            </div>
+          <!-- Leaf -->
+          <div
+            v-else
+            class="tree-item leaf-item"
+            :class="{ active: isKeySelected(item.node.fullPath), selected: isKeyMultiSelected(item.node.fullPath) }"
+            :style="{ paddingLeft: `${12 + item.level * 16}px` }"
+            @click="selectKey(item.node.fullPath, $event)"
+            @contextmenu.prevent="onKeyContextMenu($event, item.node.fullPath)"
+          >
+            <el-icon class="tree-icon"><Document /></el-icon>
+            <span class="tree-name">{{ formatKeyName(item.node.name) }}</span>
           </div>
         </template>
       </div>
@@ -945,20 +968,8 @@ onUnmounted(() => {
   font-weight: 500;
 }
 
-.tree-children {
-  padding-left: 20px;
-}
-
-.tree-children.hidden {
-  display: none;
-}
-
-.tree-spacer {
-  width: 16px;
-}
-
 .leaf-item {
-  padding-left: 12px;
+  /* padding handled by inline style based on tree depth */
 }
 
 .key-footer {