The Debian 13 (Trixie) packaging uses the distro-provided libftxui-dev
package and disables the FetchContent fallback path.

The package rules pin CMake to Qt6 with Qt6_DIR so the build remains on the
Qt6 stack even when multiple Qt major versions are installed locally.

This packaging tree uses source format 3.0 (native) so crossbuilder can create
its timestamped local source package without requiring an upstream orig tarball
from an APT source repository.
