SDL normally turns a command-line process into a permanent foreground Cocoa app. This Lisp is a durable REPL host, so we manage that policy around the actual lifetime of its windows instead.

There is no cooperating foreground application to yield activation when a Slynk worker opens a window. This is an explicit user request, so use the same forceful activation that SDL uses for command-line Cocoa apps. A process transitioning out of background-only policy needs a few Cocoa event turns before Launch Services will honor activation, so pump briefly instead of leaving a regular-but-background window in another Stage.