Add Google OAuth authentication infrastructure

- Add passport, passport-google-oauth20, jsonwebtoken, cookie-parser, uuid deps
- Create config/auth.js with JWT, cookie, and OAuth configuration
- Create models/user.js with MongoDB user model and indexes
- Create middleware/passport.js with Google OAuth strategy
- Create middleware/auth.js with requireAuth middleware and sliding window refresh
- Create routes/auth.js with OAuth flow endpoints
- Update server.js to integrate auth, protect all data endpoints (except /health)
- Configure CORS for cookie-based authentication

routes/auth.js

@@ -0,0 +1,116 @@
+const express = require('express');
+const passport = require('passport');
+const jwt = require('jsonwebtoken');
+const authConfig = require('../config/auth');
+const { requireAuth, generateToken } = require('../middleware/auth');
+
+const router = express.Router();
+
+/**
+ * GET /auth/google
+ * Initiates Google OAuth flow
+ */
+router.get('/google', passport.authenticate('google', {
+  scope: authConfig.google.scope,
+  session: false
+}));
+
+/**
+ * GET /auth/google/callback
+ * Handles OAuth callback from Google
+ * On success: generates JWT, sets cookie, redirects to frontend
+ * On failure: redirects to login with error
+ */
+router.get('/google/callback',
+  passport.authenticate('google', {
+    session: false,
+    failureRedirect: `${process.env.FRONTEND_URL}/login?error=auth_failed`
+  }),
+  async (req, res) => {
+    try {
+      const user = req.user;
+
+      // Check if email is verified (if available in profile)
+      if (req.authInfo && req.authInfo.emails && req.authInfo.emails[0]) {
+        const emailVerified = req.authInfo.emails[0].verified !== false; // Default to true if not present
+        if (!emailVerified) {
+          return res.redirect(`${process.env.FRONTEND_URL}/login?error=unverified`);
+        }
+      }
+
+      // Check if user account is active
+      if (!user.isActive) {
+        return res.redirect(`${process.env.FRONTEND_URL}/login`);
+      }
+
+      // Generate JWT token
+      const token = generateToken(user._id);
+
+      // Set auth cookie
+      res.cookie(authConfig.cookie.name, token, authConfig.cookie.options);
+
+      // Redirect to frontend
+      res.redirect(process.env.FRONTEND_URL);
+    } catch (err) {
+      console.error('OAuth callback error:', err);
+      res.redirect(`${process.env.FRONTEND_URL}/login?error=auth_failed`);
+    }
+  }
+);
+
+/**
+ * GET /auth/me
+ * Returns current authenticated user's data
+ * Protected route - requires valid JWT
+ */
+router.get('/me', requireAuth, (req, res) => {
+  res.json({
+    user: {
+      id: req.user._id,
+      email: req.user.email,
+      name: req.user.name,
+      picture: req.user.picture,
+      role: req.user.role
+    }
+  });
+});
+
+/**
+ * POST /auth/logout
+ * Clears authentication cookie
+ * Protected route - requires valid JWT
+ */
+router.post('/logout', requireAuth, (req, res) => {
+  // Clear the auth cookie
+  res.clearCookie(authConfig.cookie.name, {
+    ...authConfig.cookie.options,
+    maxAge: 0
+  });
+
+  res.json({ message: 'Logged out successfully' });
+});
+
+/**
+ * GET /auth/status
+ * Returns authentication status without requiring middleware
+ * Used for quick frontend checks
+ */
+router.get('/status', (req, res) => {
+  const token = req.cookies[authConfig.cookie.name];
+
+  // No token present
+  if (!token) {
+    return res.json({ authenticated: false });
+  }
+
+  try {
+    // Verify the token
+    jwt.verify(token, authConfig.jwt.secret);
+    return res.json({ authenticated: true });
+  } catch (err) {
+    // Token invalid or expired
+    return res.json({ authenticated: false });
+  }
+});
+
+module.exports = router;