Add Google OAuth integration, routing, and theme toggle; implement login and protected routes

Frontend/src/contexts/AuthContext.jsx

@@ -0,0 +1,98 @@
+import { createContext, useContext, useState, useEffect } from 'react';
+
+const AuthContext = createContext();
+
+export const useAuth = () => {
+  const context = useContext(AuthContext);
+  if (!context) {
+    throw new Error('useAuth must be used within an AuthProvider');
+  }
+  return context;
+};
+
+export const AuthProvider = ({ children }) => {
+  const [user, setUser] = useState(null);
+  const [isLoading, setIsLoading] = useState(true);
+
+  // Check for existing session on app load
+  useEffect(() => {
+    const checkAuthStatus = () => {
+      try {
+        const savedUser = localStorage.getItem('monaco_user');
+        const savedToken = localStorage.getItem('monaco_token');
+        if (savedUser && savedToken) {
+          setUser(JSON.parse(savedUser));
+        }
+      } catch (error) {
+        console.error('Error checking auth status:', error);
+        localStorage.removeItem('monaco_user');
+        localStorage.removeItem('monaco_token');
+      } finally {
+        setIsLoading(false);
+      }
+    };
+
+    checkAuthStatus();
+  }, []);
+
+  const login = async (email, googleToken, userInfo = null) => {
+    try {
+      // For Google OAuth login
+      if (googleToken && userInfo) {
+        const userData = {
+          id: userInfo.sub || Date.now(),
+          email: email,
+          name: userInfo.name || email.split('@')[0],
+          picture: userInfo.picture || null,
+          loginTime: new Date().toISOString(),
+          googleToken: googleToken
+        };
+
+        setUser(userData);
+        localStorage.setItem('monaco_user', JSON.stringify(userData));
+        localStorage.setItem('monaco_token', googleToken);
+        return true;
+      }
+      
+      // Fallback for demo purposes (though we're moving to Google-only)
+      if (email && email.includes('@')) {
+        const userData = {
+          id: Date.now(),
+          email: email,
+          name: email.split('@')[0],
+          loginTime: new Date().toISOString()
+        };
+
+        setUser(userData);
+        localStorage.setItem('monaco_user', JSON.stringify(userData));
+        localStorage.setItem('monaco_token', 'demo_token');
+        return true;
+      }
+      
+      return false;
+    } catch (error) {
+      console.error('Login error:', error);
+      return false;
+    }
+  };
+
+  const logout = () => {
+    setUser(null);
+    localStorage.removeItem('monaco_user');
+    localStorage.removeItem('monaco_token');
+  };
+
+  const value = {
+    user,
+    login,
+    logout,
+    isAuthenticated: !!user,
+    isLoading
+  };
+
+  return (
+    <AuthContext.Provider value={value}>
+      {children}
+    </AuthContext.Provider>
+  );
+};