style(ui): enlarge row action icons and rebalance clients table widths

Bump row action icons to 18px across the clients, inbounds, groups and
nodes tables for better visibility.

In the clients table, cap the Client column at 220px and give Duration a
fixed width so the Traffic column becomes the flexible one that absorbs
the remaining horizontal space instead of Client growing oversized.

frontend/src/pages/groups/GroupsPage.tsx

@@ -407,10 +407,10 @@ export default function GroupsPage() {
       render: (_v, row) => (
         <Space size={4}>
           <Dropdown trigger={['click']} menu={{ items: rowActions(row) }}>
-            <Button size="small" type="text" icon={<MoreOutlined />} />
+            <Button size="small" type="text" style={{ fontSize: 18 }} icon={<MoreOutlined />} />
           </Dropdown>
           <Tooltip title={t('pages.groups.rename')}>
-            <Button size="small" type="text" icon={<EditOutlined />} onClick={() => openRename(row)} />
+            <Button size="small" type="text" style={{ fontSize: 18 }} icon={<EditOutlined />} onClick={() => openRename(row)} />
           </Tooltip>
         </Space>
       ),