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/src/domains/dto/index.ts

@@ -0,0 +1,3 @@
+export { CreateDomainDto } from "./create-domain.dto";
+export { UpdateDomainDto } from "./update-domain.dto";
+export { QueryDomainsDto } from "./query-domains.dto";