fix(ui): route external links out of the Android VK WebView

The Android VK client's WebView ignores target=_blank and navigates the
Mini App's own window to the target, stranding the player outside the
game with no way back (the dictionary lookup, About/Feedback links, the
ad banner and the bot-link modal fallbacks). vk-bridge 3.x has no method
to open an external URL, so external links are routed through VK's own
leave-VK redirect (vk.com/away.php), which the client intercepts
natively and hands to the system browser.

onExternalLinkClick moves from lib/telegram to a new lib/links that
composes the Telegram and VK routers; iOS and desktop VK open _blank
correctly and are left alone.

ui/src/components/AdBanner.svelte

@@ -9,7 +9,7 @@
   } from '../lib/bannerEngine';
   import { defaultBannerTimings, linkify, type BannerHost } from '../lib/banner';
   import type { BannerCampaign, BannerTimings } from '../lib/model';
-  import { onExternalLinkClick } from '../lib/telegram';
+  import { onExternalLinkClick } from '../lib/links';
 
   let {
     campaigns,
@@ -112,7 +112,8 @@
 </script>
 
 <!-- The banner links are rendered via {@html}; a delegated click routes any of them through the
-     Telegram SDK (onExternalLinkClick uses closest('a')) so they skip the WebView confirmation. -->
+     platform opener (onExternalLinkClick uses closest('a')): the Telegram SDK skips the WebView
+     confirmation, the VK away-redirect keeps the Android WebView on the game. -->
 <!-- svelte-ignore a11y_no_static_element_interactions -->
 <!-- svelte-ignore a11y_click_events_have_key_events -->
 <div class="ad" bind:this={viewport} onclick={onExternalLinkClick}>

ui/src/components/StaleInviteModal.svelte

@@ -4,6 +4,7 @@
   import { t } from '../lib/i18n/index.svelte';
   import { botUsername } from '../lib/deeplink';
   import { insideTelegram, telegramDialogsAvailable, telegramOpenLink, telegramShowPopup } from '../lib/telegram';
+  import { openExternalUrl } from '../lib/links';
   import { BOT_BUTTON_ID, botInfoPopup } from '../lib/nativedialogs';
   import Modal from './Modal.svelte';
 
@@ -16,8 +17,8 @@
     if (username) {
       const url = `https://t.me/${username}`;
       // Inside Telegram, openTelegramLink navigates to the bot chat natively; elsewhere fall
-      // back to a new tab.
-      if (!telegramOpenLink(url) && typeof window !== 'undefined') window.open(url, '_blank');
+      // back to a new tab (routed out of the Android VK WebView by openExternalUrl).
+      if (!telegramOpenLink(url)) openExternalUrl(url);
     }
     dismissStaleInvite();
   }

ui/src/components/WelcomeRedeemModal.svelte

@@ -4,6 +4,7 @@
   import { t } from '../lib/i18n/index.svelte';
   import { botUsername } from '../lib/deeplink';
   import { insideTelegram, telegramDialogsAvailable, telegramOpenLink, telegramShowPopup } from '../lib/telegram';
+  import { openExternalUrl } from '../lib/links';
   import { BOT_BUTTON_ID, botInfoPopup } from '../lib/nativedialogs';
   import Modal from './Modal.svelte';
 
@@ -19,8 +20,8 @@
     if (username) {
       const url = `https://t.me/${username}`;
       // Inside Telegram, openTelegramLink navigates to the bot chat natively; elsewhere fall
-      // back to a new tab.
-      if (!telegramOpenLink(url) && typeof window !== 'undefined') window.open(url, '_blank');
+      // back to a new tab (routed out of the Android VK WebView by openExternalUrl).
+      if (!telegramOpenLink(url)) openExternalUrl(url);
     }
     dismissWelcomeRedeem();
   }