fix: the Flex panel DAX button now toggles the TRANSMIT-bar DAX (transmit set dax=), not the slice RX DAX channel — this is the button that routes TX audio through DAX (WSJT-X); state follows changes made in SmartSDR too

app.go

@@ -10968,6 +10968,15 @@ func (a *App) FlexSetDAX(ch int) error {
 	}
 	return a.cat.FlexDo(func(fc cat.FlexController) error { return fc.SetDAX(ch) })
 }
+
+// FlexSetTXDAX toggles DAX as the transmit audio source — SmartSDR's
+// transmit-bar DAX button (what WSJT-X TX audio goes through).
+func (a *App) FlexSetTXDAX(on bool) error {
+	if a.cat == nil {
+		return fmt.Errorf("cat not initialized")
+	}
+	return a.cat.FlexDo(func(fc cat.FlexController) error { return fc.SetTXDAX(on) })
+}
 func (a *App) FlexSetTXFilter(low, high int) error {
 	if a.cat == nil {
 		return fmt.Errorf("cat not initialized")