loopd: close tapd client connections

Close the TapdClient when daemon initialization fails, during normal
shutdown, and after the view command completes. This prevents gRPC
transport resources from leaking across embedded daemon lifecycles and
error paths.

loopd/daemon.go

@@ -158,6 +158,15 @@ func (d *Daemon) Start() error {
 		if err != nil {
 			return err
 		}
+
+		defer func() {
+			if err == nil || d.assetClient == nil {
+				return
+			}
+
+			d.assetClient.Close()
+			d.assetClient = nil
+		}()
 	}
 
 	// With lnd connected, initialize everything else, such as the swap
@@ -178,15 +187,15 @@ func (d *Daemon) Start() error {
 
 	// If we get here, we already have started several goroutines. So if
 	// anything goes wrong now, we need to cleanly shut down again.
-	startErr := d.startWebServers()
-	if startErr != nil {
-		errorf("Error while starting daemon: %v", startErr)
+	err = d.startWebServers()
+	if err != nil {
+		errorf("Error while starting daemon: %v", err)
 		d.Stop()
 		stopErr := <-d.ErrChan
 		if stopErr != nil {
 			errorf("Error while stopping daemon: %v", stopErr)
 		}
-		return startErr
+		return err
 	}
 
 	return nil
@@ -1145,6 +1154,10 @@ func (d *Daemon) stop() {
 	if d.clientCleanup != nil {
 		d.clientCleanup()
 	}
+	if d.assetClient != nil {
+		d.assetClient.Close()
+		d.assetClient = nil
+	}
 
 	// Everything should be shutting down now, wait for completion.
 	d.wg.Wait()

loopd/view.go

@@ -44,6 +44,7 @@ func view(config *Config, lisCfg *ListenerCfg) error {
 		if err != nil {
 			return err
 		}
+		defer assetClient.Close()
 	}
 
 	swapClient, cleanup, err := getClient(