fix: backend refinement

[mkw2107]

Issue/Ticket

Trello card

Description

Refactored the existing backend code. It is still in JavaScript and AWS SDK V2 for now, but the next step will be to migrate to AWS SDK V3 and TypeScript.

Reproduction steps

add your .env for AWS credentials npm intall npm start

Checklist

• [x] I've followed the Contributing guidelines
• [x] I've titled my PR according to the Conventional Commits spec
• [x] I've added tests that fail without this PR but pass with it
• [x] I've linted, tested, and commented my code
• [x] I've updated documentation (if appropriate)