The icon-only rail switcher now shows the active language code as a small corner badge,
so the current language reads at a glance without opening the menu.
- Split the rail into a content group (Feed/Channels/Playlists) and an admin
group (Stats/Scheduler) separated by a divider (system group hidden for non-admins).
- Move the language switcher, About and notification bell out of the top header
into an icon cluster above Settings (horizontal expanded, vertical collapsed).
Their popovers portal to <body> and anchor right + above the button, escaping the
nav's backdrop-filter. About is removed from the account popover (now in the cluster).
- LanguageSwitcher/NotificationCenter gain a 'rail' variant for the above.
- Also relocate the Toaster mount into the (now relative) content column.
Floating menus hover over undimmed content (no backdrop scrim like dialogs), so the
frosted .glass (78%) let the content bleed through and hurt readability. Add a near-opaque
.glass-menu (surface 92%, keeps blur) and use it for the account, language, notification
and add-to-playlist popovers. Dialogs/chrome keep the frostier .glass (they sit over a dark
scrim / the ambient bg). perf-mode disables its blur too.
Set up react-i18next with locale files auto-loaded per area (Vite glob), a compact
LanguageSwitcher, and language as a server-persisted preference (preferences.language)
mirrored to localStorage. On first login the default UI language is guessed from the
Google-reported locale (hu/en/de, else English). vite-env.d.ts types the build-time env.
