RE.10 Unreal in the browser edition: we host Unreal and send the picture back

A browser cannot run Unreal (native C++, no web build) or reach one on the person's computer, so the web edition can only save the Unreal folder as a zip today (RE.5). To give it Unreal pictures, Unreal must run on a machine we provide: the browser sends the RE.2 scene package, a GPU server renders the chosen camera through Movie Render Queue, the PNG comes back to the Render dialog labelled "Drawn by Unreal Engine". Needs a render service and queue (accounts, limits, timeouts, cost per picture), a GPU host (the VPS has none), and the plug-in proven in a real Unreal first (RE.5 never ran there). Recommended first if any of this is done.

Not promising soon (owner 2026-11-06). Licensing points are from memory, not checked against Epic's terms. Full write-up: docs/spikes/RE-unreal-hosted.md.