Implementar modo oscuro con toggle en sidebar

src/contexts/ThemeContext.tsx

@@ -0,0 +1,40 @@
+import { createContext, useContext, useEffect, useState, type ReactNode } from 'react';
+
+interface ThemeContextType {
+  isDarkMode: boolean;
+  toggleDarkMode: () => void;
+}
+
+const ThemeContext = createContext<ThemeContextType | undefined>(undefined);
+
+export function ThemeProvider({ children }: { children: ReactNode }) {
+  const [isDarkMode, setIsDarkMode] = useState(() => {
+    const saved = localStorage.getItem('darkMode');
+    return saved ? JSON.parse(saved) : false;
+  });
+
+  useEffect(() => {
+    localStorage.setItem('darkMode', JSON.stringify(isDarkMode));
+    if (isDarkMode) {
+      document.documentElement.classList.add('dark');
+    } else {
+      document.documentElement.classList.remove('dark');
+    }
+  }, [isDarkMode]);
+
+  const toggleDarkMode = () => setIsDarkMode((prev: boolean) => !prev);
+
+  return (
+    <ThemeContext.Provider value={{ isDarkMode, toggleDarkMode }}>
+      {children}
+    </ThemeContext.Provider>
+  );
+}
+
+export function useTheme() {
+  const context = useContext(ThemeContext);
+  if (!context) {
+    throw new Error('useTheme must be used within ThemeProvider');
+  }
+  return context;
+}