Add default settings file support for Dank Material Shell (DMS)

- Introduced a new option `defaultSettingsFile` in the DMS configuration to allow host-specific first-run settings.
- Updated the home-manager module to read from the specified settings file if provided, otherwise falling back to the bundled defaults.
- Enhanced the documentation in the default settings file to clarify its purpose and usage.

modules/desktop/shells/dms/home-manager/default.nix

@@ -59,10 +59,14 @@
   '';
 
   jsonFormat = pkgs.formats.json { };
-  dmsSeedSettings = import ../_private/default-settings.nix {
-    inherit lib gpuTempEnabled;
-    extraRightBarWidgets = cfg.extraRightBarWidgets;
-  };
+  dmsSeedSettings =
+    if cfg.defaultSettingsFile != null then
+      builtins.fromJSON (builtins.readFile cfg.defaultSettingsFile)
+    else
+      import ../_private/default-settings.nix {
+        inherit lib gpuTempEnabled;
+        extraRightBarWidgets = cfg.extraRightBarWidgets;
+      };
   dmsSeedFile = jsonFormat.generate "dms-settings-seed.json" dmsSeedSettings;
   dmsSettingsPath = "${config.xdg.configHome}/DankMaterialShell/settings.json";
 
@@ -126,6 +130,15 @@ in {
     dms.enableRbwLockToggle = lib.mkEnableOption ''
       Ship rbw-lock-toggle into `~/.config/DankMaterialShell/plugins/rbwLockToggle/` (directory name matches plugin id; Bitwarden vault lock/unlock in the bar).
     '';
+
+    dms.defaultSettingsFile = lib.mkOption {
+      type = lib.types.nullOr lib.types.path;
+      default = null;
+      description = ''
+        Host-specific first-run `settings.json` seed. When set, replaces the bundled
+        `default-settings.nix` template on fresh profiles.
+      '';
+    };
   };
 
   imports = [