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>

packages/i18n/locales/ru/common.json

@@ -39,7 +39,8 @@
   "profile": {
     "menu": "Меню профиля",
     "settings": "Настройки",
-    "logout": "Выйти"
+    "logout": "Выйти",
+    "android_app": "Приложение для Android"
   },
   "roles": {
     "admin": "Администратор",