docs: sync VK theme-follow + home-bar safe-area into FUNCTIONAL/UI_DESIGN/.claude

The #142 polish shipped three VK behaviours the docs never picked up (they were
written for the #140 auth MVP):

- the "auto" theme follows the VK client light/dark (VKWebAppUpdateConfig), not
  the VK webview's prefers-color-scheme;
- the layout clears the VK mobile home bar via CSS env() max'd with the VK bridge
  insets (VKWebAppUpdateInsets) — the bridge value is needed on Android, where the
  VK webview exposes no env() inset (.claude said env() handled it alone);
- share/copy route through the bridge (VKWebAppShare/VKWebAppCopyText).

FUNCTIONAL (+_ru) VK paragraph gains theme+home-bar parity with the Telegram one;
UI_DESIGN gets a VK-integration note beside the Telegram one.

docs/FUNCTIONAL.md

@@ -38,7 +38,9 @@ deployment), the Mini App retries quietly and then shows a small "couldn't load"
 A **VK Mini App** launch works the same way: it authenticates from VK's signed launch parameters
 (verified by the gateway), and on first contact seeds the new account's interface language from
 `vk_language` and its display name from the VK profile (read on the client, since VK does not put
-the name in the signed launch). The same quiet-retry "couldn't load" screen applies inside VK.
+the name in the signed launch). While the theme preference is "auto" the app follows the VK
+client's light/dark scheme, and the layout clears the VK mobile home bar. The same quiet-retry
+"couldn't load" screen applies inside VK.
 Telegram runs a **single bot**: every player uses
 the same bot, and all of its chat and out-of-app notifications are written in the
 player's own **interface language** (en/ru). A separate optional **promo bot** can run alongside the