Add KDE and set it as the default on the workstation host

Note: The kde configuration is currently incomplete. It's still missing
some configuration using the plasma-manager flake. I'm going to get
plasma working first and then worry about the small configuration
details.

modules/desktop/environments/hyprland.nix

@@ -104,10 +104,10 @@
         ipc = "on";
         splash = false;
         preload = [
-          "/nix/config/assets/wallpaper.jpg"
+          "/nix/config/assets/wallpapers/hyprland.jpg"
         ];
         wallpaper = [
-          ",/nix/config/assets/wallpaper.jpg"
+          ",/nix/config/wallpapers/hyprland.jpg"
         ];
       };
     };

modules/desktop/environments/kde.nix

@@ -0,0 +1,95 @@
+{ pkgs, ... }:
+
+{
+  imports = [
+    ../../system/fonts.nix
+  ];
+
+  environment.sessionVariables = {
+    LIBVA_DRIVER_NAME = "nvidia";
+    XDG_SESSION_TYPE = "wayland";
+    GBM_BACKEND = "nvidia-drm";
+    __GLX_VENDOR_LIBRARY_NAME = "nvidia";
+    NVD_BACKEND = "direct";
+    MOZ_DISABLE_RDD_SANDBOX = 1;
+    NIXOS_OZONE_WL = 1;
+  };
+
+  services.desktopManager.plasma6.enable = true;
+  services.displayManager.sddm = {
+    enable = true;
+    wayland.enable = true;
+  };
+
+  environment.plasma6.excludePackages = with pkgs.kdePackages; [
+    plasma-browser-integration
+    khelpcenter
+    krdp
+  ];
+
+  environment.systemPackages = with pkgs; [
+    nvidia-vaapi-driver
+  ];
+
+  home-manager.users.hu = {
+    dconf.settings = {
+      "org/gnome/desktop/interface" = {
+        color-scheme = "prefer-dark";
+      };
+    };
+
+    gtk = {
+      enable = true;
+      theme = {
+        name = "breeze";
+        package = pkgs.kdePackages.breeze-gtk;
+      };
+    };
+
+    programs.plasma = {
+      enable = true;
+      workspace = {
+        lookAndFeel = "org.kde.breezedark.desktop";
+        wallpaper = "/nix/config/assets/wallpapers/kde.png";
+      };
+
+      panels = [
+        {
+          location = "bottom";
+          widgets = [
+            {
+              kickoff = {
+                icon = "nix-snowflake-white";
+              };
+            }
+            {
+              iconTasks = {
+                launchers = [
+                  "applications:org.kde.dolphin.desktop"
+                  "applications:org.kde.konsole.desktop"
+                  "applications:org.mozilla.firefox.desktop"
+                ];
+              };
+            }
+            "org.kde.plasma.marginsseperator"
+            {
+              digialclock = {
+                calendar.firstDayOfWeek = "monday";
+                time.format = "24h";
+              };
+            }
+            {
+              systemTray.items = {
+                shown = [
+                  "org.kde.plasma.networkmanagement"
+                  "org.kde.plasma.volume"
+                ];
+              };
+            }
+          ];
+        }
+      ];
+    };
+  };
+}
+