4.10 = the 1995 arcade release; 4.11 = the win32 reconstruction; the
build number is the git commit count -- monotonic, zero-maintenance,
and every exe pins to exact source via the short hash ('+' = built
from an uncommitted tree). tools/btversion.cmake regenerates
build/btversion.h on every build (write-if-changed, no rebuild churn);
the stamp shows in the boot banner (btl4.log head, replacing the stale
'v4.10' line) and the window title (incl. the MP node tag).
Verified: build stamps 4.11.311 (980c9cd+), banner + title correct on
a live boot.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
