use jovian-nixos + fixup niri display session handling

flake.nix

@@ -60,6 +60,11 @@
       url = "github:serokell/deploy-rs";
       inputs.nixpkgs.follows = "nixpkgs";
     };
+
+    jovian-nixos = {
+      url = "github:Jovian-Experiments/Jovian-NixOS";
+      inputs.nixpkgs.follows = "nixpkgs";
+    };
   };
 
   outputs =
@@ -70,6 +75,7 @@
       nixos-hardware,
       home-manager,
       deploy-rs,
+      jovian-nixos,
       ...
     }@inputs:
     let
@@ -79,6 +85,7 @@
         "mreow"
         "yarn"
       ];
+      niri-package = inputs.niri.packages.${system}.niri-unstable;
     in
     {
       formatter.${system} = nixpkgs.legacyPackages.${system}.nixfmt-rfc-style;
@@ -93,6 +100,7 @@
                 inputs
                 username
                 hostname
+                niri-package
                 ;
             };
             modules = [
@@ -103,7 +111,7 @@
                   # home-manager.useGlobalPkgs = true;
                   home-manager.useUserPackages = true;
                   home-manager.extraSpecialArgs = {
-                    inherit inputs hostname username;
+                    inherit inputs hostname username niri-package;
                     homeDirectory = "/home/${username}";
                     stateVersion = config.system.stateVersion;
                   };