Implement social authentication (GitHub/Google) for login and register forms

[coderabbitai]

Description

The login and register forms currently display GitHub and Google authentication buttons, but these buttons are non-functional. Social authentication providers are not configured in the auth setup.

Tasks

• Configure GitHub OAuth provider in src/lib/auth.ts
• Configure Google OAuth provider in src/lib/auth.ts
• Implement click handlers for social login buttons in src/features/auth/components/login-form.tsx
• Implement click handlers for social login buttons in src/features/auth/components/register-form.tsx
• Set up required OAuth credentials and environment variables

Related

• Pull Request: feat: integrate better-auth for authentication and add login/register forms #3
• Comment: feat: integrate better-auth for authentication and add login/register forms #3 (comment)
• Requested by: @Pranjal6955