The opening is a script now, not a slice in the wiring

bootOpening built its actions in boot.go and appended the finale by hand,
which made the one thing a player sees first the only content not
authored as content. inkwell's OnStart takes a script name now, so the
opening moves to script.opening.go and boot names it.

The -finale flag becomes OnFinale, the engine's hook for a closing script
queued after the start one, so the branch is a hook rather than a slice
append. bootOpening's start parameter had been dead for a while; it goes
with the function.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

go.mod

@@ -3,7 +3,7 @@ module git.teletypegames.org/games/realworld
 go 1.26.3
 
 require (
-	git.teletypegames.org/engines/inkwell v0.1.1-0.20260830083613-39af65f3c98f
+	git.teletypegames.org/engines/inkwell v0.1.1-0.20260830092549-e26f7345c14d
 	github.com/hajimehoshi/ebiten/v2 v2.9.9
 )