Fixed Issue #51

[Haseebx162006]

Fixed Login API Status Codes & Add Frontend Auth UI
This PR fixes incorrect HTTP status codes in the login API and implements a complete, professional frontend authentication system.

Backend Changes:
Replaced non-standard HTTP 444 with standard HTTP 401 for password mismatches
Changed HTTP 400 to HTTP 401 for user-not-found cases to prevent email enumeration
Ensured consistent error messages for security
Kept HTTP 400 only for missing/empty fields

Frontend Changes:
Created modern login page with professional design
Created matching registration page
Implemented complete authentication flow with JWT token storage
Added theme persistence across all pages
Added login button to main navigation
Centralized all authentication styles

Testing: Back-end logic verified via unit tests confirming all status codes work correctly:

Empty credentials return 400
Invalid email returns 401
Wrong password returns 401 (previously was 444)
Valid credentials return 200 with token

End-to-end testing requires MongoDB connection. The repository does not include a MongoDB URI environment variable, so live API testing returns server errors. Unit tests confirm the logic is correct. Repository maintainers can verify full functionality after merging by adding their MongoDB connection string to the environment.

The code is complete, tested, and ready to merge. @gbowne1 You are requested to view the changes.

[gbowne1]

@Haseebx162006

PR #50 includes a sample .env file.

I checked out this change locally for testing and review for merge.

I found that this change is able to be merged as is but has some overlap and introduces a number of new files which turns main.js into several files.

This is fine but I think it would be best if this PR landed after the other 7 have.

Feel free to review those for possible overlapping code.

Also see comments I made in Discussion tab

[shishir-21]

@Haseebx162006

These changes seem consistent with the repository structure.
One minor suggestion:

• In HTML files, please check that all elements use consistent classes (e.g., same spacing/style).
• In JS, adding a short comment explaining the error handling logic in login.js might improve clarity.

Thanks for this update.

[Haseebx162006]

@gbowne1 @shishir-21 merge conflicts have been resolved

[Ved178]

Looks good, thank you. This is ready to merge.

[Haseebx162006]

@EricKart @Mustansir-06 @abhisheksingh1204 you are requested to review this

[gbowne1]

@Haseebx162006

I'm not sure at this point if we will get reviews from those three collaborators but.. who knows 🤷‍♂️ unless we hear from them.

Right now it's only myself, @Ved178 and @shishir-21

It'll take time to find regular contributors and collaborators and maintainers. Help Wanted and Good First Issue tags on items in the Issue tab will help with this

[shishir-21]

@Haseebx162006

Reviewed the PR.
Login flow and status code handling look correct.
Nice work — approved and ready to merge. 🚀

[gbowne1]

@Haseebx162006

I checked out this change locally for testing and review for merge

It appears to add the correct fixes to improve issue #51 to login, etc.

Approving this PR for merge and merging.