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/domains.module.ts

@@ -0,0 +1,14 @@
+import { Module } from "@nestjs/common";
+import { DomainsController } from "./domains.controller";
+import { DomainsService } from "./domains.service";
+import { PrismaModule } from "../prisma/prisma.module";
+import { ActivityModule } from "../activity/activity.module";
+import { AuthModule } from "../auth/auth.module";
+
+@Module({
+  imports: [PrismaModule, ActivityModule, AuthModule],
+  controllers: [DomainsController],
+  providers: [DomainsService],
+  exports: [DomainsService],
+})
+export class DomainsModule {}