[client] wayland: use nominal refresh for frame demand

Use the current wl_output mode for the requested producer cadence.
Presentation feedback can follow a slower VRR cadence, feeding that low
update rate back into the IDD. Select the fastest nominal mode when a
window spans multiple outputs.

client/displayservers/Wayland/presentation.c

@@ -73,6 +73,12 @@ static void presentationFeedbackPresented(void * opaque,
 
 bool waylandGetFramePeriod(uint64_t * period)
 {
+  /* Frame demand must use the output's nominal rate. Basing demand on the
+   * observed presentation interval can lock a VRR session at its current,
+   * slower cadence. */
+  if (waylandOutputGetFramePeriod(period))
+    return true;
+
   const uint64_t value = atomic_load(&wlWm.presentationPeriod);
   if (!value)
     return false;