Linux capture dependencies (not bundled)

The Linux native capture process dynamically uses the distribution's XDG
Desktop Portal/libportal and GStreamer packages. Piik does not redistribute
those shared libraries. The App package carries the applicable license texts
for this linked capture path.

libportal headers and library are LGPL-3.0-only. Source:
https://github.com/flatpak/libportal/blob/main/COPYING
The full LGPL-3.0-only and GPL-3.0 texts are included in the package notice.

GStreamer and its plugins carry the license and notices of each upstream
component. The core project is LGPL-2.1-or-later; consult the installed distro
packages for the exact plugin notices. Source and licensing information:
https://gstreamer.freedesktop.org/documentation/frequently-asked-questions/licensing.html
https://gstreamer.freedesktop.org/

The runtime stack also depends on the host's Portal, PipeWire, and hardware
encoder services. Those services are not part of the Piik App package.
