feat: profile page, admin pages, infinite scroll on browse

- Add /profile page with reading settings (voice, speed, auto-next) and password change form
- Add /admin/scrape page showing scraping task history with live status polling and trigger controls
- Add /admin/audio page showing audio cache entries with client-side search filter
- Add changePassword(), listAudioCache(), listScrapingTasks() to pocketbase.ts
- Add /api/admin/scrape and /api/browse-page server-side proxy routes
- Replace browse page pagination with IntersectionObserver infinite scroll
- Update nav: username becomes a /profile link; admin users see Scrape and Audio cache links

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

@@ -0,0 +1,17 @@
+import { redirect } from '@sveltejs/kit';
+import type { PageServerLoad } from './$types';
+import { listAudioCache } from '$lib/server/pocketbase';
+import { log } from '$lib/server/logger';
+
+export const load: PageServerLoad = async ({ locals }) => {
+	if (locals.user?.role !== 'admin') {
+		redirect(302, '/');
+	}
+
+	const entries = await listAudioCache().catch((e) => {
+		log.warn('admin/audio', 'failed to load audio cache', { err: String(e) });
+		return [];
+	});
+
+	return { entries };
+};