feat: Android download page, analysis retry and a collapsible search

- /android is a public page with the latest APK, the server address to copy
  and three install steps; linked from the sign-in screen and the profile menu
- failed audio analysis can be retried from the library page, which also shows
  the most common error; the analyzer no longer burns attempts on files that
  are missing because the disk is not mounted
- the top bar search folds into a round button and slides open on click, "/"
  or Ctrl+K

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

apps/web/src/pages/admin/LibraryPage.tsx

@@ -1,5 +1,5 @@
 import { unwrap } from '@pipu/core';
-import { useMutation, useQuery } from '@tanstack/react-query';
+import { useMutation, useQuery, useQueryClient } from '@tanstack/react-query';
 import { useId } from 'react';
 import { useTranslation } from 'react-i18next';
 
@@ -32,6 +32,11 @@ export function LibraryPage() {
   const reindex = useMutation({
     mutationFn: async () => unwrap(await session.client.POST('/api/v1/admin/search/reindex')),
   });
+  const queryClient = useQueryClient();
+  const retry = useMutation({
+    mutationFn: async () => unwrap(await session.client.POST('/api/v1/admin/library/analysis/retry')),
+    onSuccess: () => void queryClient.invalidateQueries({ queryKey: ['library-status'] }),
+  });
   const d = status.data;
   const tiles = d
     ? ([
@@ -77,7 +82,19 @@ export function LibraryPage() {
               total: d.analysis.done + d.analysis.queued + d.analysis.running + d.analysis.failed,
             })}
           />
-          {d.analysis.failed > 0 && <span className={l.scanError}>{t('library.analysis_failed', { count: d.analysis.failed })}</span>}
+          {d.analysis.failed > 0 && (
+            <div className={l.retryRow}>
+              <span className={l.scanError}>
+                {t('library.analysis_failed', { count: d.analysis.failed })}
+                {d.analysis.top_error && <span className={l.errorDetail}>{d.analysis.top_error}</span>}
+              </span>
+              {admin && (
+                <Button variant="secondary" icon={refreshIcon} busy={retry.isPending} onClick={() => retry.mutate()}>
+                  {t('library.analysis_retry')}
+                </Button>
+              )}
+            </div>
+          )}
           {d.analysis.analyzer_ver && <span className={l.scanSummary}>{t('library.analyzer', { ver: d.analysis.analyzer_ver })}</span>}
         </section>
       )}

apps/web/src/pages/admin/library.module.css

@@ -118,6 +118,20 @@
   color: var(--danger);
 }
 
+.retryRow {
+  display: flex;
+  align-items: center;
+  justify-content: space-between;
+  gap: 16px;
+}
+
+.errorDetail {
+  display: block;
+  margin-top: 4px;
+  color: var(--text3);
+  word-break: break-word;
+}
+
 .bar {
   height: 6px;
   border-radius: 3px;