Refactor: Move nodemon to devDependencies, add dev scripts, update readme

[Melvin0070]

PR Description:

This PR enhances the project's development environment setup by optimizing dependencies and scripts organization:

• [x] Move nodemon to dev dependencies object
• [x] Also add separate scripts "run":"node server.js" and "dev":"nodemon server.js" in scripts obj.
• [x] Remove unwanted "test" script if there is no planning to add e2e and frontend testing in future.
• [x] Update readme.md with instruction to run server folder along with client folder