Pause Frametop for VR games

Frametop kept using the headset during games: with gaze mode off, our eye tracker still took
about 60% of a core, remote desktop about 2 cores while on, and KWin kept drawing hidden
screens because ft-screens sent their frame callbacks at 90 Hz. Pausing gives that back, and
resuming brings back only what pausing stopped. It's also a way to keep the gaze service and
our eye tracker off during games, which PR #13 asked for.

Paused (input/game_pause.py, run by the input relay):
- frametop-gaze stops (ft-eyegrab then idles by itself), and hand tracking and remote desktop
  stop if they run
- the desktop hides and slows down: ft-screens "pause on" hides every panel and sends KWin a
  frame callback once a second; or, with pause_desktop "close", the desktop closes and starts
  again on resume
- the relay lets go of the 3D mouse, typing goes to Steam, and mapped buttons and key
  combinations do only pause_toggle, steam_menu and commands

Toggled by both thumbsticks clicked together twice (configurable), read passively from
vrserver's web socket (input/vrws.py) so it works in games and takes nothing from them; by the
new pause_toggle action; by input/ft-pause; and, with pause_auto (default on), by a VR game
starting and ending, which the pointer helper now reports ("vrgame 1|0"). Frametop Input
Settings has a Games page for it. update-check.py checks the web socket, and doesn't count a
paused gaze service as failed.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

pointer/helper/ft-pointer.cpp

@@ -931,8 +931,8 @@ int main() {
     Clock::time_point handUsed{};  // a gesture began then (keeps the pointer, like gaze mode)
     Clock::time_point lastTyping{};  // the relay's last "typing": a key on a keyboard
     // Gaze mode outside games, and its dot (see the top): lastMove/lastHeld/pulseAt.
-    bool inGame = false, gazeAwake = false;
-    Clock::time_point inGameAt{}, gazeAwakeAt{};
+    bool inGame = false, gazeAwake = false, gameSent = false;
+    Clock::time_point inGameAt{}, gazeAwakeAt{}, gameSentAt{};
     Clock::time_point lastMove{}, lastHeld{}, pulseAt{};
     // The left button, as sent to the driver; pressRight: the next press is the right button
     // instead (gaze_right), heldButton: the one pressed.
@@ -1283,6 +1283,13 @@ int main() {
                 gazeAwakeAt = t;
                 SendTo(out, "frametop_relay", awake ? "gazeawake 1" : "gazeawake 0");
             }
+            // The relay pauses Frametop for VR games (input/game_pause.py). Repeated, so a relay
+            // that restarts learns it, and silence (SteamVR gone) ends the game there.
+            if (inGame != gameSent || t - gameSentAt > std::chrono::seconds(5)) {
+                gameSent = inGame;
+                gameSentAt = t;
+                SendTo(out, "frametop_relay", inGame ? "vrgame 1" : "vrgame 0");
+            }
         }
 
         // Commands from the relay.