style(frontend): even out page-bottom spacing and header sizing

Home and explore had an oversized trailing bottom padding compared to
the rest of the app; brought both down to match. Also matches "Mis
listas" grid/limit on home to "Novedades", and sizes the library page
header the same as the playlists page header.

frontend/src/routes/+page.server.ts

@@ -9,7 +9,7 @@ export const load: PageServerLoad = async ({ locals, fetch }) => {
 	});
 	const playlistsPromise = locals.user
 		? api.GET('/playlists/users/{userId}', {
-				params: { path: { userId: locals.user.sub }, query: { pageNumber: 1, pageSize: 8 } }
+				params: { path: { userId: locals.user.sub }, query: { pageNumber: 1, pageSize: 12 } }
 			})
 		: Promise.resolve({ data: undefined });
 	const recentlyPlayedPromise = locals.user