refactor(knowledge): migrate deleted-item cleanup from polling scheduler to event-driven worker

Replaces the scheduler-polled KnowledgeDeletedCleanupWorker with an
event-driven KnowledgeDeletedCleanupEventWorker in tenant-api; cleanup
events are now enqueued transactionally at delete time instead of swept
periodically. Also fixes statement_timeout parameterization in
MonitoringRetentionWorker and propagates errors from cleanupDeletedKnowledgeItem.

Co-Authored-By: Claude Sonnet 4.6 (1M context) <noreply@anthropic.com>

server/cmd/tenant-api/main.go

@@ -42,6 +42,19 @@ func main() {
 	tenantapp.NewDesktopAccountHealthSinkWorker(app.DB, app.RabbitMQ, app.Logger).Start(workerCtx)
 	imageService := tenantapp.NewImageService(app.DB, app.ObjectStorage, app.RabbitMQ, app.Logger)
 	tenantapp.NewImageAssetWorker(imageService, app.RabbitMQ, app.Logger).Start(workerCtx)
+	knowledgeCleanupService := tenantapp.NewKnowledgeService(
+		app.DB,
+		app.RetrievalProvider,
+		app.VectorStore,
+		app.ObjectStorage,
+		app.LLM,
+		app.Logger,
+		app.Config().Retrieval,
+		app.Config().LLM,
+		0,
+		0,
+	).WithConfigProvider(app.ConfigStore)
+	tenantapp.NewKnowledgeDeletedCleanupEventWorker(knowledgeCleanupService, app.Logger).Start(workerCtx)
 
 	transport.RegisterRoutes(app)