fix: purge deleted-stack notifications from panel and ticker (#1674)

* fix: purge deleted-stack notifications from panel and ticker

Stack delete already cascaded scans and drift but left notification_history rows, so the bell and Activity ticker kept showing the deleted stack. Purge those rows in the shared deletion lifecycle, invalidate connected clients, and drop node-scoped in-memory rows immediately.

* fix: target remote notification purge by hub node id

Remote stack-deleted invalidations always reconcile with hub rn.id, and
notification refetch preserves failed node slices instead of wiping them.

backend/src/services/DeployedStackDeletionService.ts

@@ -18,6 +18,7 @@ import DockerController from './DockerController';
 import { FileSystemService } from './FileSystemService';
 import { NodeRegistry } from './NodeRegistry';
 import { MeshService } from './MeshService';
+import { NotificationService } from './NotificationService';
 import { StackOpLockService, stackOpSkipMessage } from './StackOpLockService';
 import { getErrorMessage } from '../utils/errors';
 import { sanitizeForLog } from '../utils/safeLog';
@@ -248,6 +249,7 @@ export class DeployedStackDeletionService {
       db.deleteStackExposure(nodeId, stackName);
       db.deleteStackProjectEnvFiles(nodeId, stackName);
       db.deleteStackScans(nodeId, stackName);
+      db.deleteNotificationsForStack(nodeId, stackName);
     } catch (dbErr) {
       console.error(
         '[DeployedStackDeletion] Secondary DB cleanup failed for %s; recovery rows already retired:',
@@ -272,6 +274,14 @@ export class DeployedStackDeletionService {
     }
 
     await this.sweepReadyIntent(intentId);
+    NotificationService.getInstance().broadcastEvent({
+      type: 'state-invalidate',
+      scope: 'notifications',
+      action: 'stack-deleted',
+      nodeId,
+      stackName,
+      ts: Date.now(),
+    });
     return { ok: true };
   }