Refactor client update handling to support nullable parameters for name and expiration

- Updated the `UpdateClientAsync` method in `IXuiPanelGateway` to accept nullable parameters for `name` and `expiresAt`, allowing for more flexible client management without unintended modifications.
- Adjusted the `BlockUserCommandHandler`, `UnblockUserCommandHandler`, and other related command handlers to utilize the new nullable parameters, ensuring that client names remain unchanged during block/unblock operations and that expiration dates are managed correctly.
- Enhanced the billing and configuration handling to reflect the new logic for managing client states based on expiration rather than enabling/disabling, improving reliability in client status management.
- Updated tests to cover the new behavior and ensure proper functionality across the application.

frontend/src/routes/dashboard.tsx

@@ -30,6 +30,12 @@ function ConfigsList() {
   const inboundsQuery = useQuery({ queryKey: ['available-inbounds'], queryFn: listAvailableInbounds })
   const billingStatusQuery = useQuery({ queryKey: ['my-billing-status'], queryFn: getMyBillingStatus })
 
+  // Зеркалит серверную проверку в CreateVpnConfigCommandHandler (ConfigErrors.BillingRequired) —
+  // роль с биллингом и просроченной/неоплаченной подпиской не может создавать новые конфиги.
+  const billing = billingStatusQuery.data
+  const billingBlocksCreate =
+    !!billing?.billingEnabled && (billing.paidUntil == null || new Date(billing.paidUntil) < new Date())
+
   return (
     <div className="mx-auto flex w-full max-w-4xl flex-col gap-6 px-6 py-10">
       <div className="flex items-center justify-between gap-4">
@@ -52,7 +58,14 @@ function ConfigsList() {
             </Link>
           )}
         </div>
-        {inboundsQuery.data?.length === 0 ? (
+        {billingBlocksCreate ? (
+          <div className="flex max-w-xs flex-col items-end gap-1 text-right text-sm">
+            <p className="text-muted-foreground">{t('configs.billingRequiredNotice')}</p>
+            <Link to="/billing" className="font-medium text-foreground underline underline-offset-2">
+              {t('configs.goToBilling')}
+            </Link>
+          </div>
+        ) : inboundsQuery.data?.length === 0 ? (
           <p className="max-w-xs text-right text-sm text-muted-foreground">{t('configs.noInboundsNotice')}</p>
         ) : (
           inboundsQuery.data && <CreateConfigDialog inbounds={inboundsQuery.data} />