feat: add product domain and machine integration

- extend Prisma schema with products, product constructs and link tables\n- introduce product service, DTOs and includes with constructeur support\n- integrate product selections across model type skeletons, composants, pièces and machines\n- validate product requirements when building machine skeletons and payloads

src/products/products.module.ts

@@ -0,0 +1,9 @@
+import { Module } from '@nestjs/common';
+import { ProductsController } from './products.controller';
+import { ProductsService } from './products.service';
+
+@Module({
+  controllers: [ProductsController],
+  providers: [ProductsService],
+})
+export class ProductsModule {}