feat: fix recently-updated section + hideable home sections

Fix "Recently Updated" showing stale books: replace meta_updated
sorting (only changes on metadata writes) with chapters_idx sorted
by -created, so the section now reflects actual chapter activity.

Add per-section show/hide toggles on the home page, persisted in
localStorage via Svelte 5 $state. Each section header gets a small
hide button; hidden sections appear as restore chips above the footer.
Toggleable: Recently Updated, Browse by Genre, From Following.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

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

@@ -1,7 +1,7 @@
 import type { PageServerLoad } from './$types';
 import {
 	getBooksBySlugs,
-	recentlyAddedBooks,
+	recentlyUpdatedBooks,
 	allProgress,
 	getHomeStats,
 	getSubscriptionFeed
@@ -19,7 +19,7 @@ export const load: PageServerLoad = async ({ locals }) => {
 
 	try {
 		[recentBooks, progressList, stats] = await Promise.all([
-			recentlyAddedBooks(8),
+			recentlyUpdatedBooks(8),
 			allProgress(locals.sessionId, locals.user?.id),
 			getHomeStats()
 		]);