Home Manager modules for the Steam Frame

Portal fix, Steam-session keyboard layout, VR keyboard patch, hidden
apps, clipboard-sync and a Firefox Flatpak launcher, all under
steamFrame.*, plus the outer-session user-services mechanism.

flake.nix

@@ -0,0 +1,35 @@
+{
+  description = "Home Manager modules for the Valve Steam Frame (SteamOS, aarch64-linux)";
+
+  inputs = {
+    nixpkgs.url = "github:NixOS/nixpkgs/nixos-unstable";
+    clipboard-sync-src = {
+      url = "github:dnut/clipboard-sync";
+      flake = false;   # just the source; its flake outputs are x86-only
+    };
+  };
+
+  outputs = { self, nixpkgs, clipboard-sync-src }:
+  let
+    modules = {
+      session = ./modules/session.nix;
+      portal = ./modules/portal.nix;
+      keyboard-layout = ./modules/keyboard-layout.nix;
+      vr-keyboard = ./modules/vr-keyboard.nix;
+      hidden-apps = ./modules/hidden-apps.nix;
+      # Built with the consumer's pkgs; only the source comes from our input.
+      # The key lets the module system deduplicate it when it is imported both
+      # directly and through `default`.
+      clipboard-sync = {
+        key = "steam-frame-nix/clipboard-sync";
+        _file = ./modules/clipboard-sync.nix;
+        imports = [ (import ./modules/clipboard-sync.nix { inherit clipboard-sync-src; }) ];
+      };
+      firefox = ./modules/firefox.nix;
+    };
+  in {
+    homeManagerModules = modules // {
+      default = { imports = builtins.attrValues modules; };
+    };
+  };
+}