remove debug logs

[madhav2348]

Description

resolve #87
backend middleware contains debug logs that exploit authentication
backend/middleware/isAuth.js

Solution

remove those debug logs without changing any authentication logic

[madhav2348]

@akshay0611 please review

[akshay0611]

Re-verified PR #105 against issue #87.

-backend/middleware/isAuth.js no longer logs sensitive auth data (token/user id).

• Middleware behavior remains unchanged (same success path and same 401 responses).

This looks good to merge. Nice security cleanup.