- Document test_nglpdfwidget resolution (Poppler-Qt6 packages, QT6_GUI_AVAILABLE fix) - Add step-by-step new_docker_build.sh invocations with required options - Update test results: 4/7 tests pass (57%), test_nglpdfwidget passing (0.07 sec) - Document Docker image name: legatus-qt6-prebuilt:latest - Add package verification details and troubleshooting section - Update submodule reference to latest commit Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com> Entire-Checkpoint: 01M4DA63X8Z6288414YMJFPTQJ