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/ideas/dto/index.ts

@@ -0,0 +1,4 @@
+export { CreateIdeaDto } from "./create-idea.dto";
+export { CaptureIdeaDto } from "./capture-idea.dto";
+export { UpdateIdeaDto } from "./update-idea.dto";
+export { QueryIdeasDto } from "./query-ideas.dto";