Ship AppImage with bundled GTK runtime and automated releases

THIRD_PARTY_NOTICES.md

@@ -3,8 +3,21 @@
 The MIT license in this repository covers this project's own implementation,
 documentation and artwork. It does not relicense third-party software or trademarks.
 
-- Python, PyGObject, GTK, libadwaita and libdbusmenu are provided by your system,
-  not bundled here. Their respective licenses continue to apply.
+- When running from source, Python, PyGObject, GTK, libadwaita and libdbusmenu are
+  provided by your system. The AppImage bundles these libraries and their runtime
+  dependencies from Ubuntu 24.04. Their respective licenses continue to apply.
+- AppImage license/copyright texts and the package manifest are included under
+  `usr/share/doc/btd700-bundled/`; shared license texts are under
+  `usr/share/common-licenses/`. Extract with `--appimage-extract` to inspect them.
+  Exact corresponding Ubuntu source archives, package versions and build
+  instructions are downloadable beside each AppImage as
+  `*-dependency-sources.tar.gz`. These dependencies are not relicensed under MIT.
+- The AppImage type2 runtime is MIT-licensed and statically includes musl (MIT),
+  libfuse (LGPL 2.1), squashfuse (BSD), zstd (BSD) and zlib (zlib license).
+  Runtime notices are included in the image; runtime sources, build scripts,
+  libfuse sources/patches and squashfuse sources accompany the dependency archive.
+  See [AppImage build documentation](docs/APPIMAGE.md) for replacing libraries and
+  rebuilding the runtime or app.
 - The control protocol was reconstructed by examining the official Windows
   Sennheiser Dongle Control 1.0.5 application. The vendor application, decompiled
   sources, firmware and vendor graphics are not included. Provenance and references