feat: add walker and general launcher config

modules/lib/schema.nix

@@ -108,6 +108,37 @@ let
     }
   );
 
+  launcherType = lib.types.submodule (
+    { config, ... }:
+    {
+      options = {
+        package = lib.mkOption {
+          type = lib.types.package;
+        };
+
+        command = lib.mkOption {
+          type = lib.types.str;
+          default = lib.getExe config.package;
+          defaultText = lib.literalExpression "lib.getExe config.package";
+        };
+
+        commands = {
+          open = lib.mkOption {
+            type = lib.types.listOf lib.types.str;
+          };
+
+          files = lib.mkOption {
+            type = lib.types.listOf lib.types.str;
+          };
+
+          dmenu = lib.mkOption {
+            type = lib.types.listOf lib.types.str;
+          };
+        };
+      };
+    }
+  );
+
   displayType = lib.types.submodule (
     { ... }:
     {
@@ -236,6 +267,10 @@ in
         type = desktopApplicationType;
       };
 
+      options.meta.desktop.launcher = lib.mkOption {
+        type = launcherType;
+      };
+
       options.meta.pinentry.package = lib.mkOption {
         type = lib.types.package;
       };