feat(web): storage admin, search and catalog pages (M2)

- Storage admin: local folders with a folder picker and NFS sources,
  connection test, scan and full scan with live progress, enable,
  disable, delete
- path pattern editor with reorder, examples and a preview table that
  shows which pattern matched and what came from tags; compile errors
  land under the broken pattern
- Library page with counters, scans and unreadable files; search
  reindex for admins
- search box in the top bar: combobox with keyboard navigation, 150 ms
  debounce, cancelled stale requests, "/" and Ctrl+K, layout fix hint
- search page with tabs and paging, artist and album pages, album
  cards and track lists; unavailable tracks are dimmed

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

apps/web/src/pages/NotFound.tsx

@@ -0,0 +1,19 @@
+import { ApiError } from '@pipu/core';
+import { Link } from '@tanstack/react-router';
+import { useTranslation } from 'react-i18next';
+
+import { useErrorText } from '../shared/lib/errors';
+import s from './page.module.css';
+
+/** Сущность каталога не найдена (удалена сканом) или не загрузилась. */
+export function NotFound({ error }: { error: unknown }) {
+  const { t } = useTranslation();
+  const errorText = useErrorText();
+  const missing = error instanceof ApiError && error.status === 404;
+  return (
+    <div className={s.empty} role="alert">
+      <p>{missing ? t('catalog.not_found') : errorText(error)}</p>
+      <Link to="/">{t('catalog.back_home')}</Link>
+    </div>
+  );
+}