refactor: update niri, write config in kdl, remove niri-flake

• Updated input 'nixpkgs':
  → 'github:NixOS/nixpkgs/0254eab410b90ef2420c1059f908ae777e3b02f9?narHash=sha256-/US2Ei9JHXHVBAxV4FX49Q7H5s4UNBrIiOA6Xjzgq44%3D' (2025-12-06)

• Updated input 'home-manager':
    'github:nix-community/home-manager/f4cb25928fafa9ae68660fe71f730fc820a59028?narHash=sha256-5xOuutXM7UPTUcn3uDAD8UlPQsXmqPrX81cXoDOAGcA%3D' (2025-11-26)
  → 'github:nix-community/home-manager/89c9508bbe9b40d36b3dc206c2483ef176f15173?narHash=sha256-rB45jv4uwC90vM9UZ70plfvY/2Kdygs%2BzlQ07dGQFk4%3D' (2025-12-17)

• Updated input 'nixpkgs-master':
    'github:nixos/nixpkgs/6812bcfd614abedbdb3f68d7b6554eda6ca3e014?narHash=sha256-sNF/PZcuzYBHKRBkerEiPf5mkZM15A3fWD%2BlqpwKc60%3D' (2025-12-15)
  → 'github:nixos/nixpkgs/e50ab9bb181f9fb3ce00e7a6007c70ddaa007203?narHash=sha256-acPMRCAPgPykzkwATwD1EfF7xgmbraAvIJyCeR6bKxc%3D' (2025-12-18)

Signed-off-by: Ryan Yin <xiaoyin_c@qq.com>

home/linux/gui/niri/default.nix

@@ -2,7 +2,6 @@
   pkgs,
   config,
   lib,
-  niri,
   ...
 }@args:
 let
@@ -11,27 +10,6 @@ in
 {
   options.modules.desktop.niri = {
     enable = lib.mkEnableOption "niri compositor";
-    settings = lib.mkOption {
-      type =
-        with lib.types;
-        let
-          valueType =
-            nullOr (oneOf [
-              bool
-              int
-              float
-              str
-              path
-              (attrsOf valueType)
-              (listOf valueType)
-            ])
-            // {
-              description = "niri configuration value";
-            };
-        in
-        valueType;
-      default = { };
-    };
   };
 
   config = lib.mkIf cfg.enable (
@@ -42,7 +20,35 @@ in
           xwayland-satellite
         ];
 
-        programs.niri.config = cfg.settings;
+        xdg.configFile =
+          let
+            mkSymlink = config.lib.file.mkOutOfStoreSymlink;
+            confPath = "${config.home.homeDirectory}/nix-config/home/linux/gui/niri/conf";
+          in
+          {
+            "niri/config.kdl".source = mkSymlink "${confPath}/config.kdl";
+            "niri/keybindings.kdl".source = mkSymlink "${confPath}/keybindings.kdl";
+            "niri/spawn-at-startup.kdl".source = mkSymlink "${confPath}/spawn-at-startup.kdl";
+            "niri/windowrules.kdl".source = mkSymlink "${confPath}/windowrules.kdl";
+          };
+
+        systemd.user.services.niri-flake-polkit = {
+          Unit = {
+            Description = "PolicyKit Authentication Agent provided by niri-flake";
+            After = [
+              "graphical-session.target"
+            ];
+            Wants = [ "graphical-session-pre.target" ];
+          };
+          Install.WantedBy = [ "niri.service" ];
+          Service = {
+            Type = "simple";
+            ExecStart = "${pkgs.kdePackages.polkit-kde-agent-1}/libexec/polkit-kde-authentication-agent-1";
+            Restart = "on-failure";
+            RestartSec = 1;
+            TimeoutStopSec = 10;
+          };
+        };
 
         # NOTE: this executable is used by greetd to start a wayland session when system boot up
         # with such a vendor-no-locking script, we can switch to another wayland compositor without modifying greetd's config in NixOS module
@@ -56,10 +62,6 @@ in
           executable = true;
         };
       }
-      (import ./settings.nix niri)
-      (import ./keybindings.nix niri)
-      (import ./spawn-at-startup.nix niri)
-      (import ./windowrules.nix niri)
     ]
   );