fix: stream real frames from yolo instead of a black picture

Three separate faults, each producing a black Moonlight stream:

- sunshine's wlr backend takes wlr-screencopy's dmabuf path, which on this
  virtio-gpu returns empty buffers. Reproduced locally over 127.0.0.1, so it
  is not the network or the client. Switch to kms capture.
- hypridle locked the session and cut dpms, blanking the captured output with
  no console to unlock from. Disable it on this host.
- qemu picked the nvidia render node by readdir order, so virgl fell back to
  llvmpipe. Pin renderD128 via the VM's args.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

home/yolo/default.nix

@@ -39,6 +39,10 @@
   programs.agentSkills.machine = "yolo";
   programs.nh.flake = lib.mkForce "/home/naps62/tea/nixos-config";
 
+  # Idle lock and dpms-off blank the virtual output: Sunshine then captures a
+  # flat frame and Moonlight goes black, with no console to unlock from.
+  services.hypridle.enable = lib.mkForce false;
+
   # Blur and shadow cost a fullscreen pass per frame, and every frame here is
   # also x264-encoded for the stream — on a virtio-gpu with no VirGL, in software.
   wayland.windowManager.hyprland.extraConfig = ''