Implement the Outbox Pattern in the game.

A new level will be added to the Knative Educational Game to represent the DataRef Pattern following the ideas in #44

This issue will also be taken up after completing #44

Parent issue #8

Start by reading issue #44 and parent issue #8 to resolve whether this level should represent the Outbox Pattern or the DataRef Pattern, and to understand the expected dependency order. Review the game's existing level conventions, then consider the work done when the new level accurately teaches the agreed pattern.

Written by the indexing model from the issue text.