Replace native GFN (impossible on this GPU) with browser GFN + Moonlight

The native GeForce NOW client hard-requires Vulkan video-decode
extensions (error 0xC0F11312) and the BC-250 has no video decode
hardware — unfixable at driver level. Replaced with:
- Chromium + a GeForce NOW web-app shortcut (works on Linux Chromium
  without UA tricks nowadays; CPU-decoded 1080p)
- Moonlight client for streaming from a home Sunshine host (planned:
  VM with RTX 3050 passthrough on the R730)
Drops bc250-gfn-install service/script.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

OPERATIONS.md

@@ -110,7 +110,10 @@ high clocks. Change one thing at a time and re-check `sensors`.
 - Minecraft: open Prism Launcher, add an account (Microsoft sign-in — a paid
   Minecraft: Java Edition license on that account), then create an instance
   for the version/modpack you want. Prism downloads its own Java.
-- GeForce NOW (beta) installs itself on first boot with internet. The BC-250
-  has no hardware video decode, so the stream decodes on the CPU: keep it at
-  1080p (higher settings will stutter and run hot). If it's missing, check
-  `systemctl status bc250-gfn-install` — it retries on the next boot.
+- GeForce NOW: use the "GeForce NOW" app (a Chromium web shortcut). The
+  native GFN app cannot work on this GPU — it requires hardware video
+  decode (error 0xC0F11312) that the BC-250 physically lacks. Streams
+  decode on CPU: keep to 1080p.
+- Moonlight (installed): streams games from a home PC/server running
+  Sunshine — pair it against the host's `https://<host>:47990` panel.
+  Best-quality "cloud" gaming in the house: LAN latency, no subscription.