portal-agent: setup behind the Astra Portal run

Developer uses image generation to give Astra a visual target and gets a 3D game for a couple percent of weekly quota.

Short clip of an Astra-built game with movement, items and physics made from scratch.

Astra recreates several well-known games in turn, including Clash of Clans, Fortnite, Rocket League and Terraria.

Theo shows a game Astra created in a single prompt running in the browser, as evidence the model is unusually strong at Blender and three-dimensional reasoning.