fix(ui): exit infinite spinner with a retry card on failed initial load

List pages wrapped content in <Spin spinning={!fetched}> where 'fetched' only flipped true once data arrived. With staleTime: Infinity + retry: 1, a transient network error on first load left the query in a permanent error state and the spinner stuck forever.

Now 'fetched' also settles on query.isError, and a failed load shows a Result error card with a Refresh button that self-heals when the backend returns, mirroring the existing XrayPage pattern. Applied to clients, inbounds, groups, nodes, and the dashboard.

Fixes #4723

frontend/src/hooks/useClients.ts

@@ -213,7 +213,8 @@ export function useClients() {
   const total = listQuery.data?.total ?? 0;
   const filtered = listQuery.data?.filtered ?? 0;
   const allGroups = listQuery.data?.groups ?? [];
-  const fetched = listQuery.data !== undefined;
+  const fetched = listQuery.data !== undefined || listQuery.isError;
+  const fetchError = listQuery.error ? (listQuery.error as Error).message : '';
   const loading = listQuery.isFetching;
 
   const inbounds = inboundOptionsQuery.data ?? [];
@@ -532,6 +533,7 @@ export function useClients() {
     onlines,
     loading,
     fetched,
+    fetchError,
     subSettings,
     ipLimitEnable,
     tgBotEnable,