fix: UserManagementPage delete error feedback, input disable, date guard

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/admin/users/UserManagementPage.jsx

@@ -47,7 +47,8 @@ const tdStyle = {
 
 const formatDate = (dateStr) => {
   if (!dateStr) return '—';
-  return new Date(dateStr).toLocaleDateString('ru-RU');
+  const d = new Date(dateStr);
+  return isNaN(d) ? '—' : d.toLocaleDateString('ru-RU');
 };
 
 const UserManagementPage = () => {
@@ -59,6 +60,7 @@ const UserManagementPage = () => {
 
   const [confirmDeleteId, setConfirmDeleteId] = useState(null);
   const [deleting, setDeleting] = useState(false);
+  const [deleteError, setDeleteError] = useState('');
 
   const handleInvite = async (e) => {
     e.preventDefault();
@@ -76,13 +78,14 @@ const UserManagementPage = () => {
 
   const handleDeleteConfirm = async (userId) => {
     setDeleting(true);
+    setDeleteError('');
     try {
       await deleteUser(userId);
-    } catch {
-      // deletion errors surface in the hook's error state
-    } finally {
       setDeleting(false);
       setConfirmDeleteId(null);
+    } catch (err) {
+      setDeleting(false);
+      setDeleteError(err?.message ?? 'Ошибка удаления');
     }
   };
 
@@ -128,6 +131,7 @@ const UserManagementPage = () => {
               value={inviteEmail}
               onChange={(e) => setInviteEmail(e.target.value)}
               required
+              disabled={inviting}
               style={inputStyle}
             />
             <button
@@ -191,6 +195,7 @@ const UserManagementPage = () => {
                     <td style={tdStyle}>{formatDate(user.last_sign_in_at)}</td>
                     <td style={{ ...tdStyle, textAlign: 'right', whiteSpace: 'nowrap' }}>
                       {confirmDeleteId === user.id ? (
+                        <span style={{ display: 'inline-flex', flexDirection: 'column', alignItems: 'flex-end', gap: '4px' }}>
                           <span style={{ display: 'inline-flex', alignItems: 'center', gap: '8px' }}>
                             <span style={{ fontSize: '0.82rem', color: 'var(--text-muted)' }}>
                               Вы уверены?
@@ -214,7 +219,7 @@ const UserManagementPage = () => {
                               Удалить
                             </button>
                             <button
-                            onClick={() => setConfirmDeleteId(null)}
+                              onClick={() => { setConfirmDeleteId(null); setDeleteError(''); }}
                               disabled={deleting}
                               style={{
                                 padding: '4px 10px',
@@ -231,6 +236,12 @@ const UserManagementPage = () => {
                               Отмена
                             </button>
                           </span>
+                          {deleteError && (
+                            <span style={{ fontSize: '0.78rem', color: '#ef4444' }}>
+                              {deleteError}
+                            </span>
+                          )}
+                        </span>
                       ) : (
                         <button
                           onClick={() => setConfirmDeleteId(user.id)}