feat(sub): allow identity tokens on every subscription link (#5935)

Keep usage tokens first-link-only while adding an opt-in setting for repeating EMAIL and USERNAME in subscription-body remarks.

Co-authored-by: x06579 <x06579@ai-dashboard>

internal/sub/remark_vars_test.go

@@ -652,3 +652,40 @@ func TestEmailOnFirstLinkOnly(t *testing.T) {
 		t.Fatalf("second link should still carry the inbound name: %q", second)
 	}
 }
+
+func TestIdentityOnAllLinks(t *testing.T) {
+	const template = "{{INBOUND}}-{{EMAIL}}|{{USERNAME}}|📊{{TRAFFIC_LEFT}}|{{STATUS_EMOJI}}"
+	inbound := &model.Inbound{
+		Remark: "DE",
+		ClientStats: []xray.ClientTraffic{{
+			Email:  "alice@x",
+			Enable: true,
+			Total:  100 * gb,
+			Up:     20 * gb,
+		}},
+	}
+	tests := []struct {
+		name       string
+		enabled    bool
+		wantSecond string
+	}{
+		{name: "disabled", wantSecond: "DE"},
+		{name: "enabled", enabled: true, wantSecond: "DE-alice@x|alice@x"},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			s := &SubService{
+				remarkTemplate:         template,
+				subscriptionBody:       true,
+				showIdentityOnAllLinks: tt.enabled,
+			}
+			client := model.Client{Email: "alice@x"}
+			if got := s.genTemplatedRemark(inbound, client, "", "ws"); got != "DE-alice@x|alice@x|📊80.00GB|✅" {
+				t.Fatalf("first link = %q", got)
+			}
+			if got := s.genTemplatedRemark(inbound, client, "", "ws"); got != tt.wantSecond {
+				t.Fatalf("second link = %q, want %q", got, tt.wantSecond)
+			}
+		})
+	}
+}