swarm-ui: version the alerts table's saved-filters key

The state column stopped being a filter, so a saved "not Pending" selection
under the old key would hide every row. A new key makes the page ignore it.

frontend/packages/swarm-ui/src/pages/AlertsPage.tsx

@@ -32,6 +32,10 @@ const GRAFANA_ALERTS_URL =
 
 const FIRING = "Alerting";
 
+// Versioned: the state column used to be a filter, and a saved "not Pending"
+// selection under the old key would now hide every row.
+const FILTERS_STORAGE_KEY = "swarm-ui:alerts:table-filters:v2";
+
 // Grafana reports an instance that never became active with the zero time,
 // which `Date.parse` reads as year 1.
 function activeSinceMs(a: Alert): number | null {
@@ -139,7 +143,7 @@ export function AlertsPage() {
           columns={COLUMNS}
           rows={firing}
           rowKey={alertKey}
-          storageKey="swarm-ui:alerts:table-filters"
+          storageKey={FILTERS_STORAGE_KEY}
         />
       ) : null}
     </Panel>