fix: add missing Node column header in flat list view

addresses #370 - the table headers were missing the Node column when in flat/list view mode, causing all columns after VMID to be misaligned by one position

frontend-modern/src/components/Dashboard/Dashboard.tsx

@@ -694,6 +694,14 @@ export function Dashboard(props: DashboardProps) {
                 >
                   VMID {sortKey() === 'vmid' && (sortDirection() === 'asc' ? '▲' : '▼')}
                 </th>
+                <Show when={groupingMode() === 'flat'}>
+                  <th 
+                    class="px-2 py-1.5 text-left text-[11px] sm:text-xs font-medium uppercase tracking-wider w-[100px] cursor-pointer hover:bg-gray-200 dark:hover:bg-gray-600"
+                    onClick={() => handleSort('node')}
+                  >
+                    Node {sortKey() === 'node' && (sortDirection() === 'asc' ? '▲' : '▼')}
+                  </th>
+                </Show>
                 <th 
                   class="px-2 py-1.5 text-left text-[11px] sm:text-xs font-medium uppercase tracking-wider w-[100px] cursor-pointer hover:bg-gray-200 dark:hover:bg-gray-600"
                   onClick={() => handleSort('uptime')}

frontend-modern/src/components/Dashboard/GuestRow.tsx

@@ -155,7 +155,6 @@ export function GuestRow(props: GuestRowProps) {
         {props.guest.vmid}
       </td>
 
-
       {/* Node (optional) */}
       <Show when={props.showNode}>
         <td class="p-1 px-2 text-sm text-gray-600 dark:text-gray-400">