protofsm: implement the actor.ActorBehavior interface for StateMachine

diff --git a/protofsm/actor_wrapper.go b/protofsm/actor_wrapper.go
new file mode 100644
index 0000000..b0be9a0
--- /dev/null
+++ b/protofsm/actor_wrapper.go
@@ -0,0 +1,23 @@
+package protofsm
+
+import (
+	"fmt"
+
+	"github.com/lightningnetwork/lnd/actor"
+)
+
+// ActorMessage wraps an Event, in order to create a new message that can be
+// used with the actor package.
+type ActorMessage[Event any] struct {
+	actor.BaseMessage
+
+	// Event is the event that is being sent to the actor.
+	Event Event
+}
+
+// MessageType returns the type of the message.
+//
+// NOTE: This implements the actor.Message interface.
+func (a ActorMessage[Event]) MessageType() string {
+	return fmt.Sprintf("ActorMessage(%T)", a.Event)
+}
diff --git a/protofsm/state_machine.go b/protofsm/state_machine.go
index b3e16f5..b0c376c 100644
--- a/protofsm/state_machine.go
+++ b/protofsm/state_machine.go
@@ -259,6 +259,26 @@ func (s *StateMachine[Event, Env]) SendEvent(ctx context.Context, event Event) {
 	}
 }
 
+// Receive processes a message and returns a Result. The provided context is the
+// actor's internal context, which can be used to detect actor shutdown
+// requests.
+//
+// NOTE: This implements the actor.ActorBehavior interface.
+func (s *StateMachine[Event, Env]) Receive(ctx context.Context,
+	e ActorMessage[Event]) fn.Result[bool] {
+
+	select {
+	case s.events <- e.Event:
+		return fn.Ok(true)
+
+	case <-ctx.Done():
+		return fn.Err[bool](ctx.Err())
+
+	case <-s.quit:
+		return fn.Err[bool](ErrStateMachineShutdown)
+	}
+}
+
 // CanHandle returns true if the target message can be routed to the state
 // machine.
 func (s *StateMachine[Event, Env]) CanHandle(msg msgmux.PeerMsg) bool {