License: GPL-3.0-or-later

Full GPL-3.0 text in LICENSE, SPDX-License-Identifier header on every
source file, README license section updated. Copyright (C) 2026 Knutwurst.

Tidied a couple of stale comments in patchdl_tile.{c,h} while at it.

README.md

@@ -93,4 +93,9 @@ PS5_HOST=<console-ip> scripts/deploy_ps5.sh
 
 ## License
 
-by Knutwurst
+PatchDL is released under the **GNU General Public License v3.0 or later**.
+See [LICENSE](LICENSE) for the full text. In short: you're free to use, study,
+modify and share it — and any fork or derivative work has to stay under the
+same license.
+
+Copyright © 2026 Knutwurst.