server: update default port to 9384

[osortega]

What changed

• updated the Express server's default port from 824 to 9384 in index.js
• kept the rendered homepage status text and startup log aligned automatically via the shared port constant

Why

• the session request was to run the server on port 9384

Reviewer notes

• the branch diff is limited to this one port change
• npm test currently fails because the repository's existing test script is the placeholder echo "Error: no test specified" && exit 1; no additional validation scripts are defined in package.json