fix(gost): use chain.NewNode() to properly initialize marker for failover

When creating temporary Node instances with struct literals like
&chain.Node{Addr: host}, the marker field was not initialized.
Only chain.NewNode() properly initializes marker = selector.NewFailMarker().

Without a valid marker:
- Failed nodes cannot be marked (marker.Mark() is no-op on nil)
- Subsequent selections cannot filter out failed nodes
- Failover mechanism completely fails

Fixed locations:
- sniffer.go dial(): &chain.Node{Addr: host} -> chain.NewNode("", host)
- sniffer.go dialTLS(): &chain.Node{Addr: host} -> chain.NewNode("", host)
- local/handler.go: target := &chain.Node{} -> var target *chain.Node
- remote/handler.go: &chain.Node{Addr: host} -> chain.NewNode("", host)

go-gost/x/internal/util/forwarder/sniffer.go

@@ -263,9 +263,7 @@ func (h *Sniffer) dial(ctx context.Context, conn net.Conn, req *http.Request, ho
 		// Select a node, excluding previously tried nodes
 		selectCtx := ctxvalue.ContextWithExcludeNodes(ctx, triedNodes)
 
-		node = &chain.Node{
-			Addr: host,
-		}
+		node = chain.NewNode("", host)
 		if ho.Hop != nil {
 			node = ho.Hop.Select(selectCtx,
 				hop.ClientIPSelectOption(net.ParseIP(ro.ClientIP)),
@@ -903,9 +901,7 @@ func (h *Sniffer) dialTLS(ctx context.Context, host string, ho *HandleOptions) (
 
 		node = nil
 		if host != "" {
-			node = &chain.Node{
-				Addr: host,
-			}
+			node = chain.NewNode("", host)
 		}
 		if ho.Hop != nil {
 			node = ho.Hop.Select(selectCtx,