Serverless Product Catalog API

Problem/Feature Description

Our e-commerce team needs a lightweight serverless API to manage a small product catalog. The API will be consumed by a single-page web application running in the browser, so cross-origin requests need to be handled properly. The API should support creating, reading, updating, and deleting products using standard HTTP methods. Products should be stored persistently with a reasonable expiration time. Each product has an id, name, price, and category.

The API should be built as a PubNub Function that handles incoming HTTP requests and performs CRUD operations against persistent storage. The web frontend will call this endpoint directly from the browser.

Output Specification

Produce the following files:

1. product-api.js -- The complete PubNub Function source code for the HTTP endpoint.
2. deployment.md -- Instructions covering how to deploy the function, including what type of function trigger to select, and any necessary setup steps.