Feat/detect port env in js scripts

[tagadearpit]

Summary

Motivation

Related issue

Changes

Verification

Screenshots

Checklist

• One change per PR — one bug, or one agreed feature, with nothing unrelated bundled in
• The diff is scoped — no reformatting or lint fixes on lines I wasn't otherwise changing
• A test fails without this change and passes with it (or I explained above why there isn't one)
• bun run test, bun run --cwd <workspace> lint, and bun format all pass locally
• I understand every line of this diff and can explain it in review