Add license to kissy source code

kissy.c

@@ -1,5 +1,23 @@
-/* KISSY (KISSY Interface for Sapphic Smooching over ttY) v1.0 by Magdalunaa
+// KISSY (Kissing Interface for Sapphic Smooching over ttY) v1.0
 
+/*
+    Copyright (C) 2025  Magdalunaa <magdalunaa@linuxposting.xyz>
+
+    This program 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
+    (at your option) any later version.
+
+    This program 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.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with this program.  If not, see <https://www.gnu.org/licenses/>.
+*/
+
+/*
 This file needs to:
 - be owned by the tty group (or whatever group owns the terminal devices in your system)
 - have setgid set