Prepare TunnelX for open-source release

LICENSE

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+SPDX-License-Identifier: GPL-3.0-or-later
+
+TunnelX is free software: you can redistribute it and/or modify it under
+the terms of the GNU General Public License as published by the Free
+Software Foundation, either version 3 of the License, or any later version.
+
+TunnelX is distributed in the hope that it will be useful, but WITHOUT ANY
+WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
+FOR A PARTICULAR PURPOSE.
+
+The full GPL-3.0 license text is available at:
+https://www.gnu.org/licenses/gpl-3.0.txt
+
+Bundled third-party components, including Xray-core, sing-box, WinDivert,
+Wintun, and GeoIP/GeoSite data, remain under their own licenses. See
+THIRD_PARTY_NOTICES.md before redistributing release builds.