feat(ui): paint VK status bar to the app theme (VKWebAppSetViewSettings)

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.

docs/UI_DESIGN.md

@@ -153,7 +153,11 @@ e2e and the screenshots.
   `…NotificationOccurred` / `…SelectionChanged`), through the shared `lib/haptics.ts` dispatcher; and
   VK's **horizontal swipe-back** is disabled at launch (`VKWebAppSetSwipeSettings`) so it does not
   fight the app's own edge-swipe-back and tile drag — parity with Telegram's disabled vertical
-  swipes, the app owning navigation through its back chevron.
+  swipes, the app owning navigation through its back chevron. VK's **status bar** (and, on Android,
+  the action / navigation bars) is painted to the app theme via `VKWebAppSetViewSettings` on launch
+  and every theme change — parity with the Telegram chrome painting (`syncVKChrome` mirrors
+  `syncTelegramChrome`); the status-bar appearance follows the `--bg` token's luminance
+  (`appearanceForBg`).
 
 ## Tiles & board