server: update port and add smoke tests

[osortega]

Summary

• keep the server configured on port 1245
• make index.js export the Express app and port while only listening when run directly
• replace the placeholder failing npm test script with lightweight Node smoke tests

Why

• the session change updates the app to the requested port
• the repository previously had no meaningful passing validation because npm test intentionally failed
• exporting the app enables simple request-level tests without changing runtime behavior

Validation

• npm test

Notes for reviewers

• this PR includes the earlier port-change commit already present on the branch plus a follow-up commit that makes repository validation real and passing