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>

inc/script.opening.go

@@ -0,0 +1,16 @@
+package inc
+
+import (
+	inkwell "git.teletypegames.org/engines/inkwell"
+)
+
+func init() {
+	ScriptManager.Register(Script{
+		Name: ScriptOpening,
+		Actions: inkwell.Seq(
+			inkwell.SetFlag(FlagPoliceTip),
+			inkwell.Say(Paul, "Back alley. Just like the clerk said."),
+			TapeSay(Dex, "A government office tipped you off to remove something from a scene. That doesn't strike you as odd?"),
+		),
+	})
+}