Settings-page prefs (theme/scheme/dark-mode/list-view/perf/hints/font + the
notification settings) were each auto-saved to the server on every toggle via
fire-and-forget savePrefs().catch(() => {}) — silent on failure, and no
positive confirmation on success, so the user had zero feedback either way.
Make them a draft instead: changes apply locally for instant preview but
persist only on an explicit Save (or revert on Discard). App owns the live
draft + the last-saved baseline, computes dirty, and exposes a controller to
the panel. The panel shows a Save/Discard bar with 'Saving…' → 'Settings
saved' (auto-clearing) / 'Couldn't save' feedback. Leaving the page with
unsaved changes prompts a confirm (in-app nav + browser Back), and a
beforeunload guards reload/close. savePrefs is now idempotent so the Save
survives a transient gateway blip; failures surface via the connection-lost
status. Language & sidebar layout stay instant (edited outside this page).
New i18n keys settings.save.* / settings.unsaved.* in EN/HU/DE.
Login page quietly probes /auth/demo (debounced) as a valid email is
typed/pasted and reloads into the app on a match — no visible button.
Demo sessions default to the whole library, get a one-time shared-account
warning, never see the YouTube-connect onboarding/access UI or sync
actions, and admins get a demo whitelist + reset panel in Settings.
Feed, VideoCard, Sidebar, PlayerModal, Channels, Stats, SettingsPanel,
OnboardingWizard, NotificationCenter, Toaster, ErrorBoundary and the relativeTime
helper are now fully translated in Hungarian, English and German, each with its own
locale area file (auto-loaded). Key parity verified across all three languages.
