hyprland: add snixembed for X11 tray icon bridging (Battle.net)

Wine/XWayland apps use X11 embed tray protocol which waybar's SNI-based
tray doesn't see. snixembed proxies X11 tray icons as SNI items.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

settings/hyprland.nix

@@ -243,6 +243,7 @@ in
               hl.exec_cmd("hyprctl setcursor Bibata-Modern-Ice 24")
               hl.exec_cmd("swayosd-server")
               ${lib.optionalString isMacbook ''hl.exec_cmd("hypridle")''}
+              ${lib.optionalString isGaming ''hl.exec_cmd("${pkgs.snixembed}/bin/snixembed --fork")''}
             end)
 
             -- Animation curve and definitions