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

apps/web/src/components/layout/Navigation.tsx

@@ -10,6 +10,7 @@ export function Navigation() {
   const { user } = useAuth();
 
   const navItems = [
+    { href: "/", label: "Dashboard" },
     { href: "/tasks", label: "Tasks" },
     { href: "/calendar", label: "Calendar" },
   ];
@@ -19,7 +20,7 @@ export function Navigation() {
       <div className="container mx-auto px-4">
         <div className="flex items-center justify-between h-16">
           <div className="flex items-center gap-8">
-            <Link href="/tasks" className="text-xl font-bold text-gray-900">
+            <Link href="/" className="text-xl font-bold text-gray-900">
               Mosaic Stack
             </Link>
             <div className="flex gap-4">