Fix Flatpak CI build: allow network access for pip install step flatpak-builder sandboxes module builds without network access by default, but "pip3 install PyQt6 ." needs to reach PyPI. This app isn't distributed via Flathub review, so granting build-time network access for this module (via --share=network) is the pragmatic fix rather than vendoring every PyQt6 wheel as a pinned source. Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>