Initial commit: OpenRA game engine

Fork from OpenRA/OpenRA with one-click launch script (start-ra.cmd)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

packaging/linux/openra-server.in

@@ -0,0 +1,10 @@
+#!/bin/sh
+set -o errexit || exit $?
+
+cd "{GAME_INSTALL_DIR}"
+
+if test -f "OpenRA.Server"; then
+	./OpenRA.Server Game.Mod={MODID} "$@"
+else
+	dotnet OpenRA.Server.dll Game.Mod={MODID} "$@"
+fi