Add SubHomePage component and minor styling updates

Introduced the SubHomePage component to enhance modularity of the home page. Adjusted styling to include margins and a dark mode class for the body element.

apps/frontend/src/components/sub-pages/sub-home-page.tsx

@@ -0,0 +1,14 @@
+import { useState } from 'react';
+
+
+export interface SubHomePageProps {
+
+}
+
+export function SubHomePage(props: SubHomePageProps) {
+  const [isLoaded, setIsLoaded] = useState<boolean>(false);
+
+  return (<section className={"w-full h-full rounded bg-card"}>
+
+  </section>)
+}