# Real-Time Product Updates

- **Complexity:** High
- **Stack:** Full-stack (Backend + Frontend)

**As a** customer, **I want to** see product changes in real time **so that** I always have up-to-date information without refreshing the page.

## Description

When an admin updates a product (price, description, availability) via the existing `ProductController` endpoints, other users only see the change after a manual page refresh. This story adds WebSocket-based push updates so all connected clients receive product changes instantly. The frontend `ProductService` currently uses Angular Signals to manage product state - real-time events should integrate with this existing reactive pattern.

## Acceptance Criteria

- [ ] Creating a product in one browser session adds it to another session's `product-catalog-page` immediately
- [ ] Updating a product in one session reflects immediately in another session's product list
- [ ] Deleting a product in one session removes it from another session's product list
- [ ] The `product-detail-page` updates live when the displayed product is modified
- [ ] If a product is deleted while a user is viewing it, a notification is shown (via `NotificationService`) and the user is redirected to the catalog
- [ ] The client reconnects automatically after a WebSocket connection drop
- [ ] Failed mutations (validation errors) do not publish events

