编辑器体验改进

- 导入文件后直接关闭弹窗 + toast 提示导入数量
- 自动布局改为按出口顺序的子树居中：选项1/2/3 分支顺序正确且对齐

web/static/app.js

@@ -210,14 +210,16 @@
   }
 
   $("import-do").onclick = async () => {
-    $("import-result").classList.add("err"); $("import-result").style.color = "";
+    $("import-result").textContent = "";
     let events;
     try { events = await collectImportEvents(); } catch (e) { $("import-result").textContent = e.message; return; }
     if (!events.length) { $("import-result").textContent = "请先选择文件或粘贴 JSON"; return; }
     const r = await api("/api/import", { method: "POST", body: JSON.stringify({ events, by: App.by }) });
     const d = await r.json();
-    $("import-result").textContent = "已导入 " + (d.saved || []).length + " 个" + ((d.errors || []).length ? "，" + d.errors.join("；") : "");
     importFiles = []; renderImportFiles(); $("import-text").value = "";
+    $("import-modal").classList.add("hidden");              // 导入完直接关闭
+    const ne = (d.errors || []).length;
+    toast("已导入 " + (d.saved || []).length + " 个事件" + (ne ? "，" + ne + " 个跳过/出错" : ""));
     await loadList();
   };
 
@@ -241,6 +243,14 @@
 
   // ---------- 工具 ----------
   function esc(s) { return String(s == null ? "" : s).replace(/&/g, "&amp;").replace(/</g, "&lt;").replace(/>/g, "&gt;"); }
+  let toastTimer = null;
+  function toast(msg) {
+    let el = $("toast");
+    if (!el) { el = document.createElement("div"); el.id = "toast"; document.body.appendChild(el); }
+    el.textContent = msg; el.classList.add("show");
+    clearTimeout(toastTimer);
+    toastTimer = setTimeout(() => el.classList.remove("show"), 2600);
+  }
 
   // ---------- 画布工具栏 ----------
   $("btn-autolayout").onclick = () => {