fix(frontend): constrain auto-import dialog width and rename duplicate filter label

- TemplatesPage: cap auto-import dialog at sm:max-w-md so it no longer
  spans the full screen (bare DialogContent defaults to near-full width).
- InstancesPage: the server (multi-server/cluster) filter wrongly reused
  the `instances.all_nodes` i18n key, so it rendered "Все узлы" identically
  to the node filter. Add a dedicated `instances.all_servers` key (RU/EN)
  and use it, so the two filters read "Все серверы" / "Все узлы".

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

frontend/src/features/instances/InstancesPage.tsx

@@ -716,7 +716,7 @@ export default function InstancesPage() {
               <SelectValue placeholder={t('backups.select_server', 'Server')} />
             </SelectTrigger>
             <SelectContent>
-              <SelectItem value="all">{t('instances.all_nodes', 'All servers')}</SelectItem>
+              <SelectItem value="all">{t('instances.all_servers', 'All servers')}</SelectItem>
               {servers.map((s) => (
                 <SelectItem key={s.id} value={String(s.id)}>{s.name}</SelectItem>
               ))}

frontend/src/features/templates/TemplatesPage.tsx

@@ -141,7 +141,7 @@ export default function TemplatesPage() {
 
       {/* Import Dialog */}
       <Dialog open={importDialogOpen} onOpenChange={setImportDialogOpen}>
-        <DialogContent>
+        <DialogContent className="sm:max-w-md">
           <DialogHeader>
             <DialogTitle>{t('templates.auto_import')}</DialogTitle>
           </DialogHeader>