Export selfupdate.Restart

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

selfupdate/restart_unix.go

@@ -7,7 +7,7 @@ import (
 	"syscall"
 )
 
-// restart replaces this process with the new binary, with the same arguments and environment.
-func restart(exe string) error {
+// Restart replaces this process with the new binary, with the same arguments and environment.
+func Restart(exe string) error {
 	return syscall.Exec(exe, os.Args, os.Environ())
 }