feat(billing): start demos on the core plan and apply tariff levels

New signups get the core module set with the 7-day demo. Superadmin can apply core, team, organization, or dedicated and the owner's environments take that level's access.

Co-authored-by: Cursor <cursoragent@cursor.com>

apps/api/src/platform/dto.ts

@@ -13,7 +13,7 @@ import {
   MinLength,
   ValidateIf,
 } from 'class-validator';
-import { USER_ROLES, type UserRole } from '@mento/shared';
+import { PRODUCT_PLAN_CODES, USER_ROLES, type ProductPlanCode, type UserRole } from '@mento/shared';
 
 export class PlatformLoginDto {
   @IsString()
@@ -189,6 +189,11 @@ export class SetStorageQuotaDto {
   quotaGb!: number | null;
 }
 
+export class ApplyProductPlanDto {
+  @IsIn(PRODUCT_PLAN_CODES)
+  planCode!: ProductPlanCode;
+}
+
 export class UpdateOrgModulesDto {
   @IsArray()
   @IsString({ each: true })