feat: Gaming on NVIDIA is not offered any more, the SteamOS conversion covers NVIDIA PCs

The conversion installs the patched gamescope on every NVIDIA PC and sets up the kernel parameters, suspend memory and 32-bit libraries on a supported card; it turns off an existing Gaming on NVIDIA.

lib/nvidia.sh

@@ -37,11 +37,21 @@ nvidia_present() {
     return 1
 }
 
-# The SteamOS conversion with the patched gamescope (lib/gamescope-nvidia.sh) replaces this on a supported card, so
-# this is for older NVIDIA cards, and for a PC where it is already on (so it can be turned off, or swapped for the
-# conversion). It and the conversion exclude each other (both would start Steam at login): the menu unticks one when
-# the other is ticked.
-nvidia_available() { nvidia_present && { ! nvidia_supported || nvidia_status; }; }
+# Not offered any more (2.11.2): the SteamOS conversion with the patched gamescope (lib/gamescope-nvidia.sh) covers NVIDIA PCs.
+# A PC that has this on keeps it until the conversion is turned on, which calls nvidia_swap_out.
+nvidia_available() { return 1; }
+
+nvidia_swap_out() {
+    # The conversion takes over: Steam no longer starts by itself on the desktop at login (both would start it). Steam, the
+    # packages and the NVIDIA settings stay: the conversion needs them too. The state stays for the conversion's own disable.
+    nvidia_status || return 0
+    info "Gaming on NVIDIA is replaced by the SteamOS conversion: Steam no longer starts on the desktop at login."
+    user_systemctl disable --now "$NVIDIA_UNIT" >/dev/null 2>&1
+    rm -f "$(nvidia_unit_file)"
+    user_systemctl daemon-reload
+    krevert bigpicture
+    return 0
+}
 bigpicture_available() { nvidia_available; }
 
 nvidia_status() {