feat: add domains, ideas, layouts, widgets API modules

- Add DomainsModule with full CRUD, search, and activity logging
- Add IdeasModule with quick capture endpoint
- Add LayoutsModule for user dashboard layouts
- Add WidgetsModule for widget definitions (read-only)
- Update ActivityService with domain/idea logging methods
- Register all new modules in AppModule

packages/ui/src/components/Button.tsx

@@ -1,7 +1,7 @@
 import type { ButtonHTMLAttributes, ReactNode } from "react";
 
 export interface ButtonProps extends ButtonHTMLAttributes<HTMLButtonElement> {
-  variant?: "primary" | "secondary" | "danger";
+  variant?: "primary" | "secondary" | "danger" | "ghost";
   size?: "sm" | "md" | "lg";
   children: ReactNode;
 }
@@ -19,6 +19,7 @@ export function Button({
     primary: "bg-blue-600 text-white hover:bg-blue-700",
     secondary: "bg-gray-200 text-gray-900 hover:bg-gray-300",
     danger: "bg-red-600 text-white hover:bg-red-700",
+    ghost: "bg-transparent text-gray-700 hover:bg-gray-100 border border-gray-300",
   };
 
   const sizeStyles = {