build: add reproducible release bundles

cmd/rvbox-server/main.go

@@ -26,12 +26,22 @@ import (
 	"google.golang.org/grpc"
 )
 
+// buildVersion is set by scripts/release for published artifacts. Development
+// and test builds intentionally retain the explicit non-release value.
+var buildVersion = "dev"
+
 func main() {
 	var configPath string
 	var checkConfig bool
+	var version bool
 	flag.StringVar(&configPath, "config", "", "absolute server TOML configuration path")
 	flag.BoolVar(&checkConfig, "check-config", false, "validate server configuration and exit")
+	flag.BoolVar(&version, "version", false, "print build version and exit")
 	flag.Parse()
+	if version {
+		fmt.Fprintln(os.Stdout, buildVersion)
+		return
+	}
 	if configPath == "" {
 		log.Print("rvbox-server: --config is required")
 		os.Exit(2)