feat(theme): add theme toggle component and integrate into sidebar

frontend/src/providers/theme-provider.tsx

@@ -0,0 +1,11 @@
+"use client";
+
+import type * as React from "react";
+import { ThemeProvider as NextThemesProvider } from "next-themes";
+
+export function ThemeProvider({
+	children,
+	...props
+}: React.ComponentProps<typeof NextThemesProvider>) {
+	return <NextThemesProvider {...props}>{children}</NextThemesProvider>;
+}