Using Postman to test backend endpoints

Our express application is started listening on a PORT.
Using it I can call localhost:PORT/api/endpoint .
This of course fails if I do not provide a valid Bearer token.
Inspecting network calls to my application from the store admin uses Bearer authentication with JWT token that changes every time I reload the app screen or every one minute. Using it the request succeeds.

I have couple of questions:

1. The aforementioned PORT is changing every time the application is restarted. Checking the Ngrok tunnel forwarding address the port seems to differ. Why it differs? Is there a way of making this port static for local developments? How? (Multiple questions but related, sorry)
2. From what I understood the flow is as follow: User enters the app screen (in the Admin panel) -> FE loads skeleton-> FE sends request to app bridge -> app bridge grants session token (JWT) to FE -> FE uses token to authenticate with app BE.
   Any way to create a session token that does not expire or has a long expiration time so I can fire requests from Postman more easily?

Start with the Express application’s PORT handling, the /api/endpoint entry point, and the app bridge-to-admin-panel token flow described in the issue. Done means documenting why the local port changes, whether it can be made static, and how to obtain or use a suitable session token for Postman requests.