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/api/prisma/schema.prisma

@@ -534,6 +534,9 @@ model UserLayout {
   // Layout configuration (array of widget placements)
   layout Json @default("[]")
 
+  // Additional metadata for the layout
+  metadata Json @default("{}")
+
   createdAt DateTime @default(now()) @map("created_at") @db.Timestamptz
   updatedAt DateTime @updatedAt @map("updated_at") @db.Timestamptz