feat: add FavoritesModule with service, controller, and CRUD endpoints

Implemented FavoritesModule to manage user favorites. Includes service methods for adding, removing, and listing favorites, along with appropriate database integrations and API endpoints.

backend/src/favorites/favorites.module.ts

@@ -0,0 +1,12 @@
+import { Module } from "@nestjs/common";
+import { DatabaseModule } from "../database/database.module";
+import { FavoritesController } from "./favorites.controller";
+import { FavoritesService } from "./favorites.service";
+
+@Module({
+	imports: [DatabaseModule],
+	controllers: [FavoritesController],
+	providers: [FavoritesService],
+	exports: [FavoritesService],
+})
+export class FavoritesModule {}