fix(vk): route the Wallet public-offer link out of the Mini App WebView

The "Public offer" link in the Wallet pointed at the same-origin static
/offer/ page with a plain target=_blank anchor and no click handler. The
Android VK client ignores target=_blank and navigates its own WebView to
the page, stranding the player with no way back to the game (iOS opens a
child browser, so it was unaffected). The existing onExternalLinkClick
router could not help: it escapes only cross-origin links, and /offer/ is
same-origin (a static legal page, not an SPA route).

Add onInAppPageLinkClick, which routes a same-origin, non-SPA page out
through the host escape hatch (Telegram openLink, VK away.php) while
bypassing the cross-origin gate, and attach it to the offer link. Outside
a Mini App host it is a no-op and the anchor's own target=_blank stands.

The "Rules" (About) and ad-banner links already route correctly
(cross-origin + a handler) and are left unchanged.

ui/src/lib/links.test.ts

@@ -1,5 +1,14 @@
 import { afterEach, describe, expect, it, vi } from 'vitest';
-import { openExternalUrl } from './links';
+import { onInAppPageLinkClick, openExternalUrl } from './links';
+
+// clickInAppPage fires onInAppPageLinkClick on a fake anchor whose (already absolute) href is the
+// same-origin /offer/ page, and reports whether the click's default navigation was suppressed.
+function clickInAppPage(href = 'https://app.example/offer/') {
+  const preventDefault = vi.fn();
+  const a = { href, target: '_blank' };
+  onInAppPageLinkClick({ target: { closest: () => a }, preventDefault } as unknown as MouseEvent);
+  return preventDefault;
+}
 
 describe('openExternalUrl', () => {
   afterEach(() => vi.unstubAllGlobals());
@@ -27,3 +36,41 @@ describe('openExternalUrl', () => {
     expect(open).toHaveBeenCalledWith('https://telegram.me/some_bot', '_blank');
   });
 });
+
+describe('onInAppPageLinkClick', () => {
+  afterEach(() => vi.unstubAllGlobals());
+
+  it('routes the same-origin offer page out through the VK away redirect', () => {
+    const open = vi.fn();
+    vi.stubGlobal('location', {
+      pathname: '/vk/',
+      search: '?vk_user_id=1&vk_platform=mobile_android&sign=x',
+      href: 'https://app.example/vk/',
+      origin: 'https://app.example',
+    });
+    vi.stubGlobal('window', { open });
+    const preventDefault = clickInAppPage();
+    // Same-origin, yet still escaped: the cross-origin gate is bypassed for a non-SPA page.
+    expect(open).toHaveBeenCalledWith(
+      `https://vk.com/away.php?to=${encodeURIComponent('https://app.example/offer/')}`,
+      '_blank',
+    );
+    expect(preventDefault).toHaveBeenCalled();
+  });
+
+  it('routes the offer page through the Telegram in-app browser', () => {
+    const openLink = vi.fn();
+    vi.stubGlobal('window', { Telegram: { WebApp: { openLink } } });
+    const preventDefault = clickInAppPage();
+    expect(openLink).toHaveBeenCalledWith('https://app.example/offer/');
+    expect(preventDefault).toHaveBeenCalled();
+  });
+
+  it('leaves the anchor to its own navigation outside a Mini App host', () => {
+    const open = vi.fn();
+    vi.stubGlobal('window', { open });
+    const preventDefault = clickInAppPage();
+    expect(open).not.toHaveBeenCalled();
+    expect(preventDefault).not.toHaveBeenCalled();
+  });
+});

ui/src/lib/links.ts

@@ -4,7 +4,7 @@
 // below route an external URL through the platform's escape hatch (Telegram's openLink, VK's
 // away.php redirect) and leave the anchor's own navigation / window.open in effect elsewhere.
 
-import { routeExternalLinkInTelegram } from './telegram';
+import { routeExternalLinkInTelegram, telegramOpenExternalLink } from './telegram';
 import { routeExternalLinkInVK, vkOpenExternalUrl } from './vk';
 
 /**
@@ -20,6 +20,21 @@ export function onExternalLinkClick(e: MouseEvent): void {
   if (routeExternalLinkInTelegram(a) || routeExternalLinkInVK(a)) e.preventDefault();
 }
 
+/**
+ * onInAppPageLinkClick is the anchor click handler for a link to a standalone, same-origin page
+ * that is not part of the SPA — the static legal /offer/ page. Such a page shares the app's origin
+ * yet must still leave the Mini App WebView: opened in place it replaces the game, and the Android
+ * VK client then strands the user there with no way back. Unlike onExternalLinkClick it therefore
+ * skips the cross-origin test (the page is same-origin by design) and routes the click straight
+ * through the Telegram in-app browser (openLink) or VK's away.php redirect. Outside those hosts it
+ * is a no-op and the anchor's own target=_blank opens the page in a new tab / child browser.
+ */
+export function onInAppPageLinkClick(e: MouseEvent): void {
+  const a = (e.target as HTMLElement | null)?.closest('a');
+  if (!a) return;
+  if (telegramOpenExternalLink(a.href) || vkOpenExternalUrl(a.href)) e.preventDefault();
+}
+
 /**
  * openExternalUrl opens an external URL from code (no anchor to click): through VK's external
  * redirect inside the Android VK client, else a plain new tab. Telegram callers try their native

ui/src/screens/Wallet.svelte

@@ -7,7 +7,7 @@
   import { t, i18n, type MessageKey } from '../lib/i18n/index.svelte';
   import { executionContext, formatAmount, needsWebSpendWarning, spendableChips, type SpendContext } from '../lib/wallet';
   import { isGooglePlayBuild, purchasesHidden } from '../lib/distribution';
-  import { onExternalLinkClick, openExternalUrl } from '../lib/links';
+  import { onExternalLinkClick, onInAppPageLinkClick, openExternalUrl } from '../lib/links';
   import { gatewayOrigin } from '../lib/origin';
   import { vkPlatform, vkShowOrderBox } from '../lib/vk';
   import { telegramOpenInvoice } from '../lib/telegram';
@@ -274,7 +274,7 @@
         {/each}
         {#if packs.length > 0}
           <p class="offer" data-testid="offer">
-            <a href="/offer/" target="_blank" rel="noopener noreferrer">{t('wallet.offer')}</a>
+            <a href="/offer/" target="_blank" rel="noopener noreferrer" onclick={onInAppPageLinkClick}>{t('wallet.offer')}</a>
           </p>
         {:else if !loading}
           <p class="empty">{t('wallet.empty')}</p>