feat(ui): hide current-host sign-in row in profile

Inside a Telegram/VK Mini App the host provider is auto-linked. Once the
player also linked an email, `canUnlink` turned true and the "Unlink"
control appeared on the host platform's own row — letting them unlink the
very platform they are signed in through, which is meaningless.

Gate the Telegram row on `!insideTelegram()` and the VK row on
`!insideVK()`, reusing the runtime host detectors that already gate the
"link" buttons. Symmetric: inside TG only the TG row is hidden (the VK row
still shows, since VK is not the current host), and vice versa. The web and
native builds are unchanged (both detectors are false there); the backend
is untouched — this is a UI display gate, and `linkUnlink` still refuses to
remove the last identity.

Docs: FUNCTIONAL.md (+_ru mirror).

ui/src/screens/Profile.svelte

@@ -13,7 +13,8 @@
   import { GatewayError } from '../lib/client';
   import { connection } from '../lib/connection.svelte';
   import { gateway } from '../lib/gateway';
-  import { loginWidgetAvailable, requestTelegramLogin } from '../lib/telegram';
+  import { insideTelegram, loginWidgetAvailable, requestTelegramLogin } from '../lib/telegram';
+  import { insideVK } from '../lib/vk';
   import { startVKLink, vkWebLinkAvailable } from '../lib/vkid';
   import { t } from '../lib/i18n/index.svelte';
   import {
@@ -58,6 +59,11 @@
   let deletePhrase = $state('');
   const telegramLinkable = loginWidgetAvailable();
   const vkLinkable = vkWebLinkAvailable();
+  // Inside a host Mini App the current platform's own identity must not be managed from the
+  // profile — unlinking the very platform you are signed in through is meaningless — so that
+  // provider's linked-account row is hidden here (the web / native builds still show both).
+  const hostTelegram = insideTelegram();
+  const hostVK = insideVK();
 
   function defaultTz(): string {
     const b = browserOffset();
@@ -392,8 +398,10 @@
     <!-- Sign-in methods: bind/change an email and link/unlink providers. A returning email
          (add) triggers the merge dialog below. On the web an account can add Telegram via the
          login widget or VK via VK ID web login (a full-page redirect); inside a Mini App the
-         host provider is already linked. Email is never unlinked — it is changed. Unlink is
-         offered only when another identity remains (the backend also refuses the last one). -->
+         host provider is already linked, so its own row is hidden — the platform you are signed
+         in through cannot be unlinked from here (the other provider's row still shows). Email is
+         never unlinked — it is changed. Unlink is offered only when another identity remains
+         (the backend also refuses the last one). -->
     <section class="accounts">
       <h3>{t('profile.accountsTitle')}</h3>
 
@@ -440,7 +448,7 @@
         </div>
       {/if}
 
-      {#if p.telegramLinked}
+      {#if p.telegramLinked && !hostTelegram}
         <div class="acctrow">
           <span class="prov"><img src="telegram-logo.svg" alt="" width="18" height="18" />Telegram</span>
           {#if canUnlink}
@@ -453,7 +461,7 @@
         </button>
       {/if}
 
-      {#if p.vkLinked}
+      {#if p.vkLinked && !hostVK}
         <div class="acctrow">
           <span class="prov"><img src="vk-logo.svg" alt="" width="18" height="18" />VK</span>
           {#if canUnlink}