feat: Implement core application layout, global styling, dark mode, and essential UI components.

Frontend-Learner/plugins/theme.client.ts

@@ -0,0 +1,10 @@
+export default defineNuxtPlugin(() => {
+  // Client-side only theme initialization to prevent flash of wrong theme
+  if (process.client) {
+    const saved = localStorage.getItem('theme')
+    const isDark = saved === 'dark' || (!saved && window.matchMedia('(prefers-color-scheme: dark)').matches)
+    
+    // Apply class immediately for Tailwind
+    document.documentElement.classList.toggle('dark', isDark)
+  }
+})