feat(ui): Studio Reference redesign — editorial hi-fi aesthetic

Replaces the Spotify-clone dark theme with a warm editorial design
language inspired by hi-fi audio mastering and magazine layouts.

- Self-host Fraunces, Geist, and Geist Mono as variable WOFF2 files
  (Latin + Latin-ext + Cyrillic subsets, OFL-licensed)
- New design tokens: warm charcoal + copper accent (dark) /
  cream paper + hunter emerald (light)
- Editorial typography: Fraunces serif for display + masthead,
  Geist for UI, Geist Mono for technical readouts (timecodes, bitrates)
- Player view restyled as magazine spread with framed album art
- Mini player as glassy console strip with copper hairline glow
- Tabs as italic editorial nav with copper underline
- Browser items as gallery cards with editorial typography
- Settings as numbered sections with refined tables
- Quick Access as console rail
- Dialogs and auth modal as paper cards with mono kickers
- Subtle film-grain overlay for analog warmth
- Localized tab labels: Player → Now Spinning, Browser → Library

media_server/static/locales/en.json

@@ -126,8 +126,8 @@
   "callbacks.msg.list_failed": "Failed to load callbacks",
   "callbacks.confirm.delete": "Are you sure you want to delete the callback \"{name}\"?",
   "callbacks.confirm.unsaved": "You have unsaved changes. Are you sure you want to discard them?",
-  "tab.player": "Player",
-  "tab.browser": "Browser",
+  "tab.player": "Now Spinning",
+  "tab.browser": "Library",
   "tab.quick_access": "Quick Access",
   "tab.settings": "Settings",
   "tab.display": "Display",

media_server/static/locales/ru.json

@@ -126,8 +126,8 @@
   "callbacks.msg.list_failed": "Не удалось загрузить обратные вызовы",
   "callbacks.confirm.delete": "Вы уверены, что хотите удалить обратный вызов \"{name}\"?",
   "callbacks.confirm.unsaved": "У вас есть несохраненные изменения. Вы уверены, что хотите отменить их?",
-  "tab.player": "Плеер",
-  "tab.browser": "Браузер",
+  "tab.player": "Сейчас играет",
+  "tab.browser": "Библиотека",
   "tab.quick_access": "Быстрый Доступ",
   "tab.settings": "Настройки",
   "tab.display": "Дисплей",