feat(sub): warn when salamander settings cannot reach the client (#6177)

* feat(sub): warn when salamander settings cannot reach the client

A hysteria2 share link carries obfuscation as obfs=salamander plus
obfs-password, and nothing else. Xray's finalmask accepts more than that —
packetSize among them — and those extra settings change what the server expects
on the wire. The emitted URI then looks complete but describes a server the
client cannot reach: every standard client applies plain salamander, the server
drops the packets, and the failure is silent on both ends.

Log the unexpressible keys when building such a link, naming the inbound, so the
cause is visible instead of appearing as a client-side problem.

* fix(sub): deduplicate salamander warnings

internal/sub/salamander_uri_test.go

@@ -0,0 +1,55 @@
+package sub
+
+import (
+	"reflect"
+	"strconv"
+	"strings"
+	"testing"
+
+	"github.com/mhsanaei/3x-ui/v3/internal/database/model"
+	"github.com/mhsanaei/3x-ui/v3/internal/logger"
+)
+
+func TestExtraSalamanderKeys(t *testing.T) {
+	if got := extraSalamanderKeys(map[string]any{"password": "pw"}); len(got) != 0 {
+		t.Fatalf("expressible settings reported extras: %v", got)
+	}
+	got := extraSalamanderKeys(map[string]any{"password": "pw", "packetSize": "512-1200"})
+	if want := []string{"packetSize"}; !reflect.DeepEqual(got, want) {
+		t.Fatalf("extraSalamanderKeys = %v, want %v", got, want)
+	}
+}
+
+func TestGenHysteriaLinkWarnsOnceForUnsupportedSalamanderSettings(t *testing.T) {
+	makeInbound := func(id int, settings string) *model.Inbound {
+		return &model.Inbound{
+			Id: id, Listen: "203.0.113.1", Port: 443, Protocol: model.Hysteria,
+			Settings:       `{"version":2,"clients":[{"auth":"secret","email":"user"}]}`,
+			StreamSettings: `{"security":"tls","finalmask":{"udp":[{"type":"salamander","settings":` + settings + `}]}}`,
+		}
+	}
+	countWarnings := func(id int) int {
+		needle := "inbound " + strconv.Itoa(id) + ": salamander settings"
+		count := 0
+		for _, line := range logger.GetLogs(100, "warning") {
+			if strings.Contains(line, needle) {
+				count++
+			}
+		}
+		return count
+	}
+
+	const standardID = 910001
+	(&SubService{}).genHysteriaLink(makeInbound(standardID, `{"password":"pw"}`), "user")
+	if got := countWarnings(standardID); got != 0 {
+		t.Fatalf("password-only warning count = %d, want 0", got)
+	}
+
+	const unsupportedID = 910002
+	in := makeInbound(unsupportedID, `{"password":"pw","packetSize":"512-1200"}`)
+	(&SubService{}).genHysteriaLink(in, "user")
+	(&SubService{}).genHysteriaLink(in, "user")
+	if got := countWarnings(unsupportedID); got != 1 {
+		t.Fatalf("unsupported-settings warning count = %d, want 1", got)
+	}
+}