Clear alerts activation config on org switch

The alertsActivation store (config, activation state, active alerts,
error) was not reset on org switch. Stale config from the previous
org (thresholds, activation state) persisted until the next page
navigation triggered refreshConfig.

frontend-modern/src/stores/alertsActivation.ts

@@ -10,6 +10,7 @@ import {
   type DisplayMetricType,
   resolveMetricDisplayThresholds,
 } from '@/utils/metricThresholds';
+import { eventBus } from './events';
 
 // Create signals for activation state
 const [config, setConfig] = createSignal<AlertConfig | null>(null);
@@ -146,6 +147,14 @@ const getMetricThresholds = (
   return resolveMetricDisplayThresholds(config(), scope, metric, resourceIds);
 };
 
+eventBus.on('org_switched', () => {
+  setConfig(null);
+  applyActivationState(null);
+  setActiveAlerts([]);
+  setLastError(null);
+  setIsLoading(false);
+});
+
 // Export the store
 export const useAlertsActivation = () => ({
   // Signals