fix(traffic): keep client accounting independent of outbound counters

The traffic poll read every Xray counter in one QueryStats reply under
gRPC's default 4 MiB receive limit; past it the whole poll failed and
no client was counted, so quotas stopped being enforced. Outbound
counters carry tags derived from third-party link remarks, so one long
remark was enough.

Poll the user, inbound and outbound families separately with a 64 MiB
limit, keep counting the families that answer, and cap a subscription
link's slug at 64 runes so the tag stays small to begin with.

internal/util/link/outbound.go

@@ -1255,6 +1255,8 @@ func base64DecodeFlexible(s string) (string, error) {
 // replacing every other run of characters with a single dash.
 var slugRe = regexp.MustCompile(`[^\p{L}\p{N}]+`)
 
+const maxSlugRunes = 64
+
 func SlugRemark(remark string) string {
 	s := strings.ToLower(strings.TrimSpace(remark))
 	s = slugRe.ReplaceAllString(s, "-")
@@ -1266,6 +1268,10 @@ func SlugRemark(remark string) string {
 	for strings.Contains(s, "--") {
 		s = strings.ReplaceAll(s, "--", "-")
 	}
+	// The tag names Xray counters, a traffic row and the config; a link author picks the remark.
+	if r := []rune(s); len(r) > maxSlugRunes {
+		s = strings.TrimRight(string(r[:maxSlugRunes]), "-")
+	}
 	return s
 }
 

internal/util/link/outbound_test.go

@@ -533,6 +533,10 @@ func TestSlugAndSuggest(t *testing.T) {
 	if got := SuggestTag("ru-", "Сервер 2", 0); got != "ru-сервер-2" {
 		t.Errorf("unicode suggest tag got %q", got)
 	}
+	// The tag names Xray counters and an outbound_traffics row; a provider picks the remark.
+	if got := SlugRemark(strings.Repeat("Ab ", 1<<20)); got != strings.Repeat("ab-", 21)+"a" {
+		t.Errorf("megabyte remark slug = %.80q (%d bytes), want the first 64 runes", got, len(got))
+	}
 }
 
 // The obfs-local plugin the panel exports carries the only description of