[FEATURE] Add dedicated backend README and environment configuration guide

[KumarManglam-123]

Feature Description

Introduce a dedicated README for the backend along with a .env.example file
to clearly document backend setup, configuration, and usage.

Problem Statement

Currently, there is no centralized documentation explaining how to configure
and run the backend locally. New contributors must inspect the code to infer
environment variables, database configuration, and startup commands, which
slows onboarding and increases the chance of setup errors.

Proposed Solution

• Add a backend/README.md containing:

  • Prerequisites
  • Dependency installation steps
  • Environment setup instructions
  • Backend start command
  • Basic API or health-check example

• Add a .env.example file listing all required environment variables
  with placeholder values and comments.

Component

Backend

Alternative Solutions

• A single root-level README with a backend section could partially help,
  but a dedicated backend README would be more scalable and contributor-friendly.

Additional Context

[github-actions]

Thank you for creating this issue! 🎉

This issue is part of Social Winter of Code 2026.

Next Steps:

• A maintainer will review and assign difficulty labels (Easy/Medium/Hard)
• Feel free to ask questions in the comments
• Wait for assignment before starting work

Happy contributing! 🚀

[KumarManglam-123]

I would like to work on this issue. Please assign it to me.

[avanthikapradeep367-eng]

@AvishkarPatil Hi, I’d like to contribute to this issue under SWOC. Please assign it to me if it’s available.

[AvishkarPatil]

Hey @KumarManglam-123, Already implemented! We have backend/.env.example with all required variables and comprehensive setup documentation in root README.md and SETUP.md. Closing as completed.