Parity with the Telegram chrome painting: on a VK Mini App launch and on
every theme change, set VK's status-bar appearance (and, on Android, the
action/navigation bar colours) from the app's live theme tokens, so the VK
chrome matches the UI instead of clashing.
syncVKChrome mirrors syncTelegramChrome; the status-bar appearance is
derived from the --bg token's luminance (appearanceForBg, unit-tested).
Wired into the VK onScheme handler (fires on launch + on theme change) and
setTheme. Docs: UI_DESIGN VK integration.