feat: support durable task cancellation without foreign keys

sdk/go/worker_integration_test.go

@@ -51,6 +51,7 @@ type workerFaultGateway struct {
 	drop        atomic.Value
 	target      atomic.Value
 	dropOffline atomic.Bool
+	dropCancel  atomic.Bool
 	offline     atomic.Bool
 	mu          sync.Mutex
 	active      map[*websocket.Conn]struct{}
@@ -137,6 +138,10 @@ func newWorkerFaultGateway(t *testing.T, upstream string) *workerFaultGateway {
 				operation := operations[f.ReplyTo]
 				delete(operations, f.ReplyTo)
 				mu.Unlock()
+				if f.Type == "task.cancel" && g.dropCancel.CompareAndSwap(true, false) {
+					g.dropped <- "task.cancel"
+					return
+				}
 				if f.Type == "ack" && operation != "" && g.drop.CompareAndSwap(operation, "") {
 					if g.dropOffline.Load() {
 						g.offline.Store(true)