scripts/dev-build-version.py turns version.txt plus the head commit into
0.7.1-dev.20261019.<hash>: the -dev display string for installer names and
the native settings page, and a YYMMDD stamp for the fourth VERSIONINFO field.
apply_version.py accepts an optional fourth quad field to carry that stamp;
releases leave it at 0, so their behaviour is unchanged. The settings page's
version parser strips the -dev suffix and compares numbers, which is what
keeps the update check quiet on dev installs -- no opt-out flag needed.
