Default headed and headless launches to a maximized window (fills the
screen) on binaries at or above the same threshold as the headless
no-viewport default. Suppressed when the caller sets --window-size /
--window-position / --start-maximized or an explicit viewport; older
builds are unchanged. Version-gated via a dedicated helper sharing the
no-viewport threshold. Mirrored across Python, JS and .NET with parity tests.
The Docker image runs openbox so headed --start-maximized is honored
(bare Xvfb has no window manager; headless is unaffected).