The CI scratch directory contains a space and non-ASCII symbols to test path handling (see #34614). However, the GHA workflows override BASE_BUILD_DIR to ${{ runner.temp }}/build via the configure-environment action, bypassing the $BASE_SCRATCH_DIR/build-$HOST default from 03_test_script.sh.
The first commit fixes the NSIS template, which otherwise breaks the deploy target when paths contain spaces.
Related to #35356.