Implement Savings Products Module (CRUD)

[Olowodarey]

Nestera offers various savings products (e.g., Fixed, Flexible) to users. We need to implement a module to manage these products and user subscriptions to them.

Acceptance Criteria

• Define Prisma schemas for SavingsProduct and UserSubscription.
• Create SavingsModule, SavingsController, and SavingsService.
• Implement endpoints: GET /savings/products, POST /savings/subscribe, GET /savings/my-subscriptions.
• Admin endpoints to create/update products (POST/PATCH /admin/savings/products).
• Use DTOs with class-validator for request validation.

Useful Resources

• NestJS Controllers