fix(cluster): a disconnected server keeps its pill

The pills listed live SESSIONS, so disconnecting one made it vanish —
along with the only way back. They now list every enabled server, and a
server with no session shows as disconnected: the state you click to
undo. The address, known only while a session exists, drops out of the
tooltip rather than reading ':0'.

frontend/src/App.tsx

@@ -8124,12 +8124,23 @@ export default function App() {
                 >
                   Disconnect all
                 </Button>
-                {clusterServerStatuses.length === 0 && (
+                {clusterServers.filter((x) => x.enabled).length === 0 && (
                   <span className="text-xs text-muted-foreground italic">
                     No active sessions — configure clusters in Settings → DX Cluster.
                   </span>
                 )}
-                {clusterServerStatuses.map((s) => {
+                {clusterServers
+                  .filter((x) => x.enabled)
+                  .sort((a, b) => a.sort_order - b.sort_order)
+                  .map((srv) => {
+                  // A disconnected server has no session to report, so it has no
+                  // entry in the status list at all — the pill stands in for it
+                  // as "disconnected", which is exactly the state you click to
+                  // undo.
+                  const live = clusterServerStatuses.find((x) => x.server_id === srv.id);
+                  const s: ServerStatus = live ?? {
+                    server_id: srv.id, name: srv.name, host: '', port: 0, state: 'disconnected',
+                  };
                   const isMaster = clusterServers
                     .filter((x) => x.enabled)
                     .sort((a, b) => a.sort_order - b.sort_order)[0]?.id === s.server_id;
@@ -8159,7 +8170,7 @@ export default function App() {
                         s.state === 'error' ? 'bg-danger-muted text-danger-muted-foreground border-danger-border' :
                         'bg-muted text-muted-foreground border-border',
                       )}
-                      title={`${s.name} — ${s.state.toUpperCase()}${s.retries ? ` #${s.retries}` : ''} · ${s.host}:${s.port}${s.error ? ' — ' + s.error : ''}\n${up || busy ? t('clu.pillDisconnect') : t('clu.pillConnect')}`}
+                      title={`${s.name} — ${s.state.toUpperCase()}${s.retries ? ` #${s.retries}` : ''}${s.host ? ` · ${s.host}:${s.port}` : ''}${s.error ? ' — ' + s.error : ''}\n${up || busy ? t('clu.pillDisconnect') : t('clu.pillConnect')}`}
                     >
                       {isMaster && <span className="text-warning" title="Master (commands go here)">★</span>}
                       {s.name}