Update CHANGELOG: list migrated subfolders (./Z, ./TetraIF)

Document which subfolders were actually migrated to Qt6.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

CHANGELOG

@@ -4,6 +4,10 @@ Date: 2026-07-14
 Summary
 Migrated project to Qt 6.8: updated CMake and cmake modules for Qt6, adjusted sources for Qt6 API changes, removed Strix and added GoogleTest scaffolding, and created a reproducible Docker dev image with Qt 6.8.3.
 
+Migrated subfolders
+- ./Z: Core application libraries and widgets (nglwidgets, ngltools, ngldb, nglapplication, nglsettings, nglcompression, etc.) — full Qt6 porting, resources (qrc), Poppler Qt6 integration and tests.
+- ./TetraIF: Tetra interface modules (CoPrtCnv, PrtCnv, LogView) — compatibility updates and Qt6 API adjustments.
+
 Key changes
 - Docker: app/Dockerfile and app/run_docker.sh (install Qt 6.8.3, poppler-qt6, build Log4Qt)
 - CMake: Qt6-first shim, cmake/NGLMacros.cmake, cmake/FindPopplerQt5.cmake compatibility