Leave match results with the Menu key, as browsers keep Escape

The results prompt shows the Menu key instead of Esc, which a browser
uses to leave fullscreen. Escape still works on desktop.

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

src/menu.h

@@ -63,8 +63,8 @@ public:
     Page pages[TAB_COUNT];
     int tab = TAB_WEAPONS;
     bool isOpen = false;
-    // Whether this tick's Escape went to the menu, so nothing else takes it too.
-    bool isEscapeTaken = false;
+    // Whether the results were left this tick (by Escape or the menu control), back to the sandbox.
+    bool isLeaving = false;
 
     void update(Game& game);
     void draw(Game& game);