TUN inbound: Log the outbound interface's forwarding once; Tweak messages

Windows turns forwarding on and off a few times while Mobile Hotspot starts,
so the error is logged when forwarding comes up, not on every change, and
turning weak host send off is logged once per IP version.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

proxy/tun/tun_windows_outbound.go

@@ -28,7 +28,7 @@ type outboundGuard struct {
 	families  []winipcfg.AddressFamily
 	luid      winipcfg.LUID            // of the interface last checked
 	turnedOff []winipcfg.AddressFamily // where weak host send was turned off on it
-	reported  string                   // the forwarding problem last logged
+	reported  string                   // the forwarding problem last seen
 	stopped   bool
 }
 
@@ -71,23 +71,24 @@ func (g *outboundGuard) check() string {
 		}
 		if !slices.Contains(g.turnedOff, family) {
 			g.turnedOff = append(g.turnedOff, family)
+			errors.LogInfo(context.Background(), "[tun] weak host send turned off for ", familyName(family), " on ", name, " while the TUN runs, as Windows would ignore autoOutboundsInterface")
 		}
-		errors.LogInfo(context.Background(), "[tun] weak host send turned off for ", familyName(family), " on ", name, " while the TUN runs, as Windows would ignore autoOutboundsInterface")
 	}
 	if len(forwarding) > 0 {
-		return "forwarding is on for " + strings.Join(forwarding, " and ") + " on " + name + ", as Mobile Hotspot and Internet Connection Sharing turn it on, so Windows ignores autoOutboundsInterface there, and Xray's own connections go into the TUN and stall"
+		return "forwarding is on for " + strings.Join(forwarding, " and ") + " on " + name + " (Mobile Hotspot and Internet Connection Sharing turn it on), so Windows ignores autoOutboundsInterface there, and Xray's own connections go into the TUN and stall"
 	}
 	return ""
 }
 
-// recheck is check for a running TUN, which logs a forwarding problem once.
+// recheck is check for a running TUN, which logs a forwarding problem when it
+// comes up. (Windows may turn forwarding on and off a few times meanwhile.)
 func (g *outboundGuard) recheck() {
 	problem := g.check()
 	g.Lock()
-	changed := problem != g.reported
+	cameUp := problem != "" && g.reported == ""
 	g.reported = problem
 	g.Unlock()
-	if changed && problem != "" {
+	if cameUp {
 		errors.LogError(context.Background(), "[tun] ", problem)
 	}
 }