refactor(all): migrate from React to Next.js

src/components/ThemeProvider.tsx

@@ -1,56 +1,3 @@
-/* eslint-disable react-refresh/only-export-components */
-import * as React from 'react';
+"use client";
 
-type Theme = 'light' | 'dark' | 'system';
-type Ctx = { theme: Theme; setTheme: (t: Theme) => void };
-const ThemeContext = React.createContext<Ctx | null>(null);
-
-export function ThemeProvider({
-  children,
-  defaultTheme = 'system',
-  storageKey = 'egce-theme',
-}: {
-  children: React.ReactNode;
-  defaultTheme?: Theme;
-  storageKey?: string;
-}) {
-  const [theme, setTheme] = React.useState<Theme>(() => {
-    try { return (localStorage.getItem(storageKey) as Theme) || defaultTheme; }
-    catch { return defaultTheme; }
-  });
-
-  React.useEffect(() => {
-    const root = document.documentElement;
-    const mql = window.matchMedia('(prefers-color-scheme: dark)');
-
-    const apply = (t: Theme) => {
-      const isDark = t === 'system' ? mql.matches : t === 'dark';
-      root.classList.toggle('dark', isDark);
-    };
-
-    apply(theme);
-    const onChange = () => theme === 'system' && apply('system');
-    mql.addEventListener('change', onChange);
-    return () => mql.removeEventListener('change', onChange);
-  }, [theme]);
-
-  React.useEffect(() => {
-    try {
-      localStorage.setItem(storageKey, theme);
-    } catch (error) {
-      console.warn('Unable to persist theme preference', error);
-    }
-  }, [theme, storageKey]);
-
-  return (
-    <ThemeContext.Provider value={{ theme, setTheme }}>
-      {children}
-    </ThemeContext.Provider>
-  );
-}
-
-export function useTheme() {
-  const ctx = React.useContext(ThemeContext);
-  if (!ctx) throw new Error('useTheme must be used within ThemeProvider');
-  return ctx;
-}
+export { ThemeProvider, useTheme } from "next-themes";