[client] display: use trusted nominal cadence

Always track Wayland surface outputs alongside fractional scaling and use
RandR modes for X11 cadence. Remove render-derived feedback so a
throttled client cannot teach the producer to remain throttled.

Release scheduling after nominal output timing remains unavailable.

client/displayservers/X11/CMakeLists.txt

@@ -10,6 +10,7 @@ pkg_check_modules(DISPLAYSERVER_X11 REQUIRED IMPORTED_TARGET
   xinerama
   xcursor
   xpresent
+  xrandr
   xkbcommon
 )