Shows a small message box with version metadata + build info. Used as
a fastest possible end-user smoke check after install: double-click
drover.exe in a portable bundle (or run 'drover gui' from cmd) and
see "OK — the binary launched and the Windows API is reachable" with
the right version on screen. No network calls, no admin needed.
Implementation: cgo-free, uses only golang.org/x/sys/windows (already
pulled in by the updater package). gui_other.go is a stub so the
package still compiles on Linux for the CI smoke build.
Locally verified: built with -X main.Version=test-local, ran
'drover.exe gui' on Windows 11, message box appeared with correct
version/commit/Go runtime info.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
