Extract onPagerChanged helper from cyclePagers

A reverse-cycle handler is about to need the same re-render-and-toast
logic. Pull it out first so the behavior change that follows only has to
swap the cycle direction.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

pkg/gui/controllers/global_controller.go

@@ -159,6 +159,13 @@ func (self *GlobalController) prevScreenMode() error {
 
 func (self *GlobalController) cyclePagers() error {
 	self.c.State().GetPagerConfig().CyclePagers()
+	self.onPagerChanged()
+	return nil
+}
+
+// onPagerChanged re-renders the main view so the newly selected pager takes
+// effect, and shows a toast naming it.
+func (self *GlobalController) onPagerChanged() {
 	currentSide := self.c.Context().CurrentSide()
 	currentKey := self.c.Context().Current().GetKey()
 	if currentSide.GetKey() == currentKey ||
@@ -182,7 +189,6 @@ func (self *GlobalController) cyclePagers() error {
 		"current": strconv.Itoa(current + 1),
 		"total":   strconv.Itoa(total),
 	}))
-	return nil
 }
 
 func (self *GlobalController) canCyclePagers() *types.DisabledReason {