Plasma config updates

Set theme and terminal program explicitly, enable virtual desktops,
enable NightColor mode with default location settings.

programs/desktop/plasma6/default.nix

@@ -18,6 +18,8 @@
     workspace = {
       clickItemTo = "open";
       lookAndFeel = "org.kde.breeze.desktop";
+      theme = "breeze-light";
+      colorScheme = "BreezeLight";
       cursor = {
         theme = "volantes_cursors";
         size = 32;
@@ -76,6 +78,7 @@
             name = "org.kde.plasma.icontasks";
             config = {
               General.launchers = [
+                "applications:systemsettings.desktop"
                 "applications:org.kde.dolphin.desktop"
                 "applications:Alacritty.desktop"
                 "applications:emacs.desktop"
@@ -101,6 +104,12 @@
       ksmserver = {
         "Lock Session" = ["Screensaver" "Meta+Alt+L"];
       };
+      kwin = {
+        "Walk Through Windows" = "Meta+Tab";
+        "Walk Through Windows (Reverse)" = "Meta+Shift+Tab";
+        "Walk Through Windows of Current Application" = "Alt+`";
+        "Walk Through Windows of Current Application (Reverse)" = "Alt+¬";
+      };
     };
 
     startup.startupScript = {
@@ -110,16 +119,38 @@
       };
     };
 
-    kwin.effects = {
+    kwin = {
+      virtualDesktops = {
+        rows = 2;
+        number = 6;
+      };
+      effects = {
         translucency.enable = true;
         blur.enable = true;
         cube.enable = true;
+        dimAdminMode.enable = true;
+      };
     };
 
     configFile = {
+      kdeglobals = {
+        General = {
+          TerminalApplication = "alacritty";
+          TerminalService = "Alacritty.desktop";
+        };
+      };
       kscreenlockerrc = {
+        Daemon.Timeout = 15;
         Greeter.WallpaperPlugin = "org.kde.potd";
       };
+      kwinrc = {
+        NightColor = {
+          Active = true;
+          Mode = "Location";
+          LatitudeFixed = "51.7";
+          LongitudeFixed = "-1.2";
+        };
+      };
     };
   };
 }