feat: toast popup for save status — 'Сохранено' or error, no layout jump

src/app/admin/_components/SectionEditor.tsx

@@ -51,6 +51,7 @@ export function SectionEditor<T>({
     } catch {
       setStatus("error");
       setError("Ошибка сохранения");
+      setTimeout(() => setStatus((s) => (s === "error" ? "idle" : s)), 4000);
     }
   }, [sectionKey]);
 

src/app/admin/open-day/page.tsx

@@ -416,6 +416,7 @@ export default function OpenDayAdminPage() {
   const [classes, setClasses] = useState<OpenDayClass[]>([]);
   const [loading, setLoading] = useState(true);
   const [saving, setSaving] = useState(false);
+  const [saveStatus, setSaveStatus] = useState<"idle" | "saved" | "error">("idle");
   const [trainers, setTrainers] = useState<string[]>([]);
   const [styles, setStyles] = useState<string[]>([]);
   const [halls, setHalls] = useState<string[]>([]);
@@ -455,12 +456,18 @@ export default function OpenDayAdminPage() {
       if (saveTimerRef.current) clearTimeout(saveTimerRef.current);
       saveTimerRef.current = setTimeout(async () => {
         setSaving(true);
-        await adminFetch("/api/admin/open-day", {
-          method: "PUT",
-          headers: { "Content-Type": "application/json" },
-          body: JSON.stringify(updated),
-        });
+        try {
+          const res = await adminFetch("/api/admin/open-day", {
+            method: "PUT",
+            headers: { "Content-Type": "application/json" },
+            body: JSON.stringify(updated),
+          });
+          setSaveStatus(res.ok ? "saved" : "error");
+        } catch {
+          setSaveStatus("error");
+        }
         setSaving(false);
+        setTimeout(() => setSaveStatus("idle"), 2000);
       }, 800);
     },
     []
@@ -528,6 +535,13 @@ export default function OpenDayAdminPage() {
 
   return (
     <div className="space-y-6">
+      {saveStatus !== "idle" && (
+        <div className={`fixed bottom-4 right-4 z-50 flex items-center gap-2 rounded-lg border px-3 py-2 text-sm shadow-lg animate-in slide-in-from-right ${
+          saveStatus === "saved" ? "bg-emerald-950/90 border-emerald-500/30 text-emerald-200" : "bg-red-950/90 border-red-500/30 text-red-200"
+        }`}>
+          {saveStatus === "saved" ? "Сохранено" : "Ошибка сохранения"}
+        </div>
+      )}
       <div className="flex items-center justify-between">
         <div>
           <h1 className="text-2xl font-bold">День открытых дверей</h1>