fix: missing env variables from the env.example file

[AbdullahMukadam]

Description

This PR adds the missing environment variables to the .env.example file and organizes them with clear sectioning and comments.

Type of Change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation update
• Code refactoring
• Performance improvement
• Dependency update

Related Issues

Closes #

Changes Made

• Added missing environment variables to .env.example

Testing

• Tested locally
• Added/updated unit tests
• Added/updated integration tests
• All tests pass

Test Environment

• OS: Windows 10
• Browser: Chrome
• Node Version: 20.x

Screenshots

Fixes this problem (before)

(After)

Checklist

• My code follows the project's style guidelines
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings or errors
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes
• Any dependent changes have been merged and published

Additional Notes

This change does not affect runtime behavior. It strictly improves documentation and setup clarity for contributors and new developers.