gaming: move home module to gaming/ dir, add moonlight client toggle

Mirror the hosts/common/features/gaming/ layout on the home side: turn the
single gaming.nix into a gaming/ directory. Moonlight (the client
counterpart to the Sunshine host) becomes moonlight.nix, gated by its own
custom.gaming.moonlight option so a host can install just the streaming
client without the full launcher/Proton toolkit (custom.gaming.enable).

- gaming.nix -> gaming/default.nix (imports moonlight.nix)
- gaming/moonlight.nix: custom.gaming.moonlight -> moonlight-qt
- arrakis: import gaming module, set custom.gaming.moonlight = true
  (replaces the one-off home.packages line)
- konishi: update import path to the directory

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

home/common/programs/gaming/default.nix

@@ -9,10 +9,16 @@
 # deliberately small. The host still owns the privileged pieces (Steam FHS
 # wrapper, Sunshine, gamemode, gamescope caps) under
 # hosts/common/features/gaming.
+#
+# Per-host segregation is by option: a host imports this module and enables only
+# the pieces it wants (e.g. a laptop enables `moonlight` for streaming without
+# the full `enable` launcher/Proton toolkit).
 let
   cfg = config.custom.gaming;
 in
 {
+  imports = [ ./moonlight.nix ];
+
   options.custom.gaming = {
     enable = lib.mkEnableOption "user-space gaming tools (launchers, Proton mgmt, MangoHud)";
 

home/common/programs/gaming/moonlight.nix

@@ -0,0 +1,26 @@
+{
+  config,
+  lib,
+  pkgs,
+  ...
+}:
+# Moonlight — client counterpart to the Sunshine host
+# (hosts/common/features/gaming/sunshine.nix). User-space, so it lives here in
+# the home gaming module rather than next to the Sunshine service.
+#
+# Gated by its own option, independent of `custom.gaming.enable`: a laptop can
+# install just the streaming client without the full launcher/Proton toolkit.
+#
+# First run: launch `moonlight`, then pair to the Sunshine host by entering the
+# PIN Moonlight shows into Sunshine's web UI (https://<host>:47990). Moonlight
+# discovers hosts on the LAN via Sunshine's mDNS.
+let
+  cfg = config.custom.gaming;
+in
+{
+  options.custom.gaming.moonlight = lib.mkEnableOption "Moonlight game-streaming client";
+
+  config = lib.mkIf cfg.moonlight {
+    home.packages = [ pkgs.moonlight-qt ];
+  };
+}