feat: unified chapter picker overlay + currently reading quick-switch modal on reader

ui/src/routes/books/[slug]/chapters/[n]/+page.svelte

@@ -5,6 +5,7 @@
 	import { page } from '$app/state';
 	import AudioPlayer from '$lib/components/AudioPlayer.svelte';
 	import CommentsSection from '$lib/components/CommentsSection.svelte';
+	import CurrentlyReadingModal from '$lib/components/CurrentlyReadingModal.svelte';
 	import type { PageData } from './$types';
 	import * as m from '$lib/paraglide/messages.js';
 	import { audioStore } from '$lib/audio.svelte';
@@ -22,6 +23,9 @@
 	let settingsPanelOpen = $state(false);
 	let settingsTab = $state<'reading' | 'listening'>('reading');
 
+	// ── Currently reading modal ───────────────────────────────────────────────
+	let readingModalOpen = $state(false);
+
 	const READER_FONTS = [
 		{ id: 'system', label: 'System' },
 		{ id: 'serif',  label: 'Serif'  },
@@ -517,6 +521,18 @@
 
 <!-- Chapter heading + meta + language switcher -->
 <div class="mb-6">
+	<!-- Book title — tappable, opens Currently Reading modal -->
+	<button
+		type="button"
+		onclick={() => (readingModalOpen = true)}
+		class="flex items-center gap-1 text-(--color-muted) hover:text-(--color-brand) text-sm font-medium transition-colors mb-1.5 max-w-full"
+		title="Switch book"
+	>
+		<span class="truncate">{data.book.title}</span>
+		<svg class="w-3.5 h-3.5 shrink-0 opacity-60" fill="none" stroke="currentColor" viewBox="0 0 24 24">
+			<path stroke-linecap="round" stroke-linejoin="round" stroke-width="2" d="M19 9l-7 7-7-7"/>
+		</svg>
+	</button>
 	<p class="text-xs font-semibold text-(--color-brand) uppercase tracking-widest mb-1.5">
 		{m.reader_chapter_n({ n: String(data.chapter.number) })}
 	</p>
@@ -1315,3 +1331,11 @@
 </div>
 {/if}
 {/if}
+
+<!-- Currently Reading modal -->
+{#if readingModalOpen}
+	<CurrentlyReadingModal
+		currentSlug={data.book.slug}
+		onclose={() => (readingModalOpen = false)}
+	/>
+{/if}