Implement theme toggle functionality and refactor styles for light/dark mode support

src/main.tsx

@@ -2,10 +2,13 @@ import { StrictMode } from 'react'
 import { createRoot } from 'react-dom/client'
 import './index.css'
 import './i18n'
+import { ThemeProvider } from './contexts/ThemeContext'
 import App from './App.tsx'
 
 createRoot(document.getElementById('root')!).render(
   <StrictMode>
-    <App />
+    <ThemeProvider>
+      <App />
+    </ThemeProvider>
   </StrictMode>,
 )