feat(ui): add audio player component, presign API route, and reading progress tracking

ui/src/routes/api/presign/audio/+server.ts

@@ -0,0 +1,26 @@
+import { json, error } from '@sveltejs/kit';
+import type { RequestHandler } from './$types';
+import { presignAudio } from '$lib/server/minio';
+
+/**
+ * GET /api/presign/audio?slug=...&n=...&voice=...&speed=...
+ * Returns a presigned MinIO URL for the audio file so the browser
+ * can stream it directly without going through the server.
+ */
+export const GET: RequestHandler = async ({ url }) => {
+	const slug = url.searchParams.get('slug');
+	const n = parseInt(url.searchParams.get('n') ?? '', 10);
+	const voice = url.searchParams.get('voice') ?? undefined;
+	const speed = parseFloat(url.searchParams.get('speed') ?? '1') || 1;
+
+	if (!slug || !n || n < 1) {
+		error(400, 'Missing slug or n');
+	}
+
+	try {
+		const presignedUrl = await presignAudio(slug, n, voice, speed);
+		return json({ url: presignedUrl });
+	} catch (e) {
+		error(500, `Could not get presigned URL: ${e}`);
+	}
+};