[Feature] Google OAuth login

[fregataa]

Summary

Implement Google OAuth login for user authentication.

Prerequisites

• [Feature] OAuth infrastructure setup #20 OAuth infrastructure setup

Scope

Setup

• Create Google Cloud Console project
• Configure OAuth consent screen
• Create OAuth 2.0 credentials
• Add authorized redirect URIs

Backend

• Add Google OAuth config (client ID, secret)
• Implement Google OAuth callback handler
• Verify Google ID token
• Extract user info (email, name, profile picture)

Frontend

• Add "Sign in with Google" button
• Handle Google OAuth redirect

Environment Variables

GOOGLE_CLIENT_ID=
GOOGLE_CLIENT_SECRET=
GOOGLE_REDIRECT_URI=

Acceptance Criteria

• Users can sign up/login with Google account
• Google account linked to user profile
• Works on both web and mobile (if applicable)

References

• Google OAuth 2.0 Documentation