add Ready to Listen feature: audio book shelf on home + /listen browse page

- getBooksWithAudioCount() in pocketbase.ts aggregates done audio_jobs, deduplicates by chapter per slug, caches 5 min
- GET /api/audio/books endpoint
- home page: readyToListen shelf with headphones badge, chapter count, Listen button, hideable
- /listen page: full grid with search, sort (most narrated / A-Z / recent), empty state

ui/src/lib/server/pocketbase.ts

@@ -1165,6 +1165,60 @@ export async function getSlugsWithAudio(): Promise<Set<string>> {
 	return new Set(jobs.map((j) => j.slug));
 }
 
+/**
+ * Returns books that have at least one completed audio chapter, sorted by
+ * number of narrated chapters descending.
+ * Cached for 5 minutes (same TTL as the catalogue audio badge).
+ */
+const AUDIO_BOOKS_CACHE_KEY = 'audio:books_with_count';
+const AUDIO_BOOKS_CACHE_TTL = 5 * 60;
+
+export interface AudioBookEntry {
+	book: Book;
+	audioChapters: number;
+}
+
+export async function getBooksWithAudioCount(limit = 100): Promise<AudioBookEntry[]> {
+	const cached = await cache.get<AudioBookEntry[]>(AUDIO_BOOKS_CACHE_KEY);
+	if (cached) return cached.slice(0, limit);
+
+	// Count done jobs per slug
+	const jobs = await listAll<AudioJob>('audio_jobs', 'status="done"', 'slug');
+	const countBySlug = new Map<string, number>();
+	for (const j of jobs) {
+		// audio_jobs can have multiple voice variants for the same chapter — deduplicate
+		// by chapter number so we count chapters, not voice variants.
+		// cache_key format: "slug/chapter/voice"
+		const slug = j.slug;
+		if (!countBySlug.has(slug)) countBySlug.set(slug, 0);
+		// We'll use a Set per slug after this loop instead
+	}
+	// Build slug → Set<chapter> to deduplicate voice variants
+	const chapsBySlug = new Map<string, Set<number>>();
+	for (const j of jobs) {
+		if (!chapsBySlug.has(j.slug)) chapsBySlug.set(j.slug, new Set());
+		chapsBySlug.get(j.slug)!.add(j.chapter);
+	}
+
+	const slugs = [...chapsBySlug.keys()];
+	if (slugs.length === 0) return [];
+
+	const books = await getBooksBySlugs(slugs);
+	const bookMap = new Map(books.map((b) => [b.slug, b]));
+
+	const entries: AudioBookEntry[] = [];
+	for (const [slug, chapters] of chapsBySlug) {
+		const book = bookMap.get(slug);
+		if (!book) continue;
+		entries.push({ book, audioChapters: chapters.size });
+	}
+	// Sort by most chapters narrated first
+	entries.sort((a, b) => b.audioChapters - a.audioChapters);
+
+	await cache.set(AUDIO_BOOKS_CACHE_KEY, entries, AUDIO_BOOKS_CACHE_TTL);
+	return entries.slice(0, limit);
+}
+
 // ─── Translation jobs ─────────────────────────────────────────────────────────
 
 export interface TranslationJob {