fix(auth): standardize login field to email and fix VITE_API_BASE_URL…

[latakshsariyapatidar]

What changed?

Fixes two issues in the frontend config and login flow, and aligns the backend to use email as the auth identifier as requested by @rdodiya.

Frontend

• api.js: Replaced import.meta.env.API_BASE_URL with import.meta.env.VITE_API_BASE_URL so Vite correctly exposes the env variable instead of silently falling back to hardcoded localhost
• Login.jsx: Standardized Formik initial values, input field bindings, and validation error rendering from username → email. Added email format validation.

Backend

• LoginRequest.java: Renamed username field to email, added @Email validation
• AuthServiceImpl.java: Updated authentication logic to look up users by email
• AuthResponse.java: Updated response payload to return email field

Type

• New feature
• Bug fix
• Documentation

Testing

Tested locally — login form shows correct email validation errors, API calls hit the correct base URL, and backend authentication works with email as identifier.

Related Issue

Closes #28

Additional Notes

Changes are backward-compatible. The email field replaces username across the full auth flow as per maintainer's guidance.

[latakshsariyapatidar]

Hi @rdodiya,

I've pushed the additional changes to this PR:

• Updated CustomUserDetailsService.java to fix the hardcoded default username/password issue
• Tested the full login flow — login works correctly with the default credentials.

Please review when you get a chance. Happy to make further adjustments if needed! 🙏

[rdodiya]

Hi @latakshsariyapatidar ,
Please resolve conflicts.