fix(sunshine): use Intel rendering and recover remote Niri sessions (#268)

- render Niri on the Intel iGPU while retaining NVIDIA-connected physical outputs
- encode Sunshine streams with Intel VAAPI and wait for a Niri output before startup
- load VKMS persistently for headless sessions and configure `Virtual-1` at 2560x1600@60
- let Moonlight request the stream bitrate instead of enforcing a 20 Mbps host cap
- remove unsupported Dynamic Boost and global NVIDIA session overrides
- grant Sunshine access to virtual input devices
- add a Nushell recovery helper that starts a temporary greetd/Niri session from SSH
- identify and safely replace normal, standalone, or previous transient Niri sessions
- launch the transient service in the background and verify greetd, Niri, and Sunshine before returning
- ignore local `.worktrees` directories and keep eval regression coverage focused on structural behavior

outputs/x86_64-linux/tests/idols-ai-gpu/expected.nix

@@ -0,0 +1,8 @@
+{
+  loadsVirtualDisplay = true;
+  createsVirtualDisplay = true;
+  niriUsesIntelRenderer = true;
+  sunshineUserHasInputAccess = true;
+  sunshineStartsAfterNiri = true;
+  sunshineWaitsForNiriOutput = true;
+}

outputs/x86_64-linux/tests/idols-ai-gpu/expr.nix

@@ -0,0 +1,17 @@
+{
+  lib,
+  outputs,
+  ...
+}:
+let
+  cfg = outputs.nixosConfigurations.ai-niri.config;
+  niriHardware = builtins.readFile ../../../../hosts/idols-ai/niri-hardware.kdl;
+in
+{
+  loadsVirtualDisplay = builtins.elem "vkms" cfg.boot.kernelModules;
+  createsVirtualDisplay = lib.hasInfix "options vkms create_default_dev=1" cfg.boot.extraModprobeConfig;
+  niriUsesIntelRenderer = lib.hasInfix "/dev/dri/by-path/pci-0000:00:02.0-render" niriHardware;
+  sunshineUserHasInputAccess = builtins.elem "input" cfg.users.users.ryan.extraGroups;
+  sunshineStartsAfterNiri = builtins.elem "niri.service" cfg.systemd.user.services.sunshine.after;
+  sunshineWaitsForNiriOutput = lib.hasInfix "niri msg outputs" cfg.systemd.user.services.sunshine.preStart;
+}