New console utility (net8.0, Linux/Proton + Windows) to point a client at
a server by writing backend.txt — the single value the Prospect agent
reads. Presets for PROD/PREPROD LAN and PROD internet, plus custom URL,
certificate import (native on Windows, guided with Proton-prefix
detection on Linux) and game launch. Interactive menu + scriptable CLI
(--folder/--set). Added to the solution; not built by the server CI.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
