Fix GitHub OAuth to send correct payload to backend

- Send { code, client_id } instead of { githubAuthCode }
- Fix MobileLogin to use VITE_GITHUB_CLIENT_ID instead of REACT_APP_*
- This enables multiple GitHub OAuth apps for different frontends

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Author: gvelez17

src/containers/Login/MobileLogin.tsx

@@ -19,8 +19,9 @@ import circles from '../../assets/images/Circles.svg'
 import Ellipse from '../../assets/images/Ellipse.svg'
 import { GoogleLogin } from '@react-oauth/google'
 import { handleAuthSuccess } from '../../utils/authUtils'
+import { GITHUB_CLIENT_ID } from '../../utils/settings'
 
-const githubUrl = `https://github.com/login/oauth/authorize?client_id=${process.env.REACT_APP_GITHUB_CLIENT_ID}`
+const githubUrl = `https://github.com/login/oauth/authorize?client_id=${GITHUB_CLIENT_ID}`
 
 const MobileLogin = ({ toggleSnackbar, setSnackbarMessage, setLoading, toggleTheme, isDarkMode }: ILoginProps) => {
   const theme = useTheme()

src/containers/Login/index.tsx

@@ -63,7 +63,7 @@ const Login = ({ toggleSnackbar, setSnackbarMessage, setLoading, toggleTheme, is
     if (githubAuthCode) {
       const githubAuthUrl = '/auth/github'
       axios
-        .post(githubAuthUrl, { githubAuthCode })
+        .post(githubAuthUrl, { code: githubAuthCode, client_id: GITHUB_CLIENT_ID })
         .then(res => {
           const { accessToken, refreshToken } = res.data
           handleAuth(accessToken, refreshToken)