fix: 文件/FTP实测修复三处真Bug

- windows-system.ts: File_OpenFile 打开文件夹时 explorer.exe 成功也返回退出码1, 放行该退出码(实测验证)
- ftp.ts: FTP_CreateDir 的 cd() 改为 await, 消除 basic-ftp 并发冲突(launched a task while another one is still running, 实测验证)
- flowValidation.ts: flow.variables 空值防御, 避免旧流程JSON缺字段时渲染崩溃

实测: FileTest 32/32, FtpTest 10/10 全部通过

src/main/capabilities/ftp.ts

@@ -111,7 +111,9 @@ register("FTP_CreateDir", async (ctx, node, args) => {
   const client = await requireClient(node.id);
   const dir = requireText(args, ["dirname"], "目录名", node.id);
   await client.ensureDir(dir);
-  client.cd(dir).catch(() => {});
+  // 创建后进入该目录；必须 await，否则下个节点的命令与本次 cd 并发，
+  // basic-ftp 会以 "task while another one is still running" 关闭客户端
+  await client.cd(dir).catch(() => {});
   ctx.log("已创建目录：" + dir, "info", node.id);
   return { created: true, dir };
 });

src/main/capabilities/windows-system.ts

@@ -87,6 +87,12 @@ register("System_SetInputMethodState", async (ctx, node, args) => {
 
 register("File_OpenFile", async (ctx, node, args) => {
   const p = reqText(args, ["path"], "文件夹路径", node.id);
-  await run("explorer.exe", [p], { windowsHide: true });
+  try {
+    await run("explorer.exe", [p], { windowsHide: true });
+  } catch (error) {
+    // explorer.exe 打开成功也会返回退出码 1（Windows 已知行为），仅路径不存在时才是真失败
+    const code = (error as { code?: unknown }).code;
+    if (code !== 1) throw error;
+  }
   return { opened: true, path: p };
 });

src/renderer/src/validation/flowValidation.ts

@@ -56,7 +56,7 @@ export function validateFlow(flow: FlowDefinition, catalog: Catalog): FlowValida
   }
 
   const definedVars = new Set<string>([
-    ...flow.variables.map((item) => item.name),
+    ...(flow.variables ?? []).map((item) => item.name),
     ...flow.nodes.map((node) => node.options?.outputVar).filter(Boolean) as string[]
   ]);
   const variableRef = /\$\{\s*([A-Za-z_\u4e00-\u9fa5][\w\u4e00-\u9fa5]*)\s*(?:\.[A-Za-z_]\w*)?\s*\}/g;