feat(profile): account-deletion flow + terminal deleted screen

Profile gains a Delete-account control (durable accounts) opening a step-up dialog: a
mailed code for an email account, or the typed DELETE phrase for a platform-only one.
On success the app swaps to a terminal AccountDeleted screen ('Учётная запись удалена')
with a Close that closes the host Mini App (telegramClose / vkClose; web = no close).
Wires deleteRequest/deleteConfirm through client/transport/mock/codec; ru/en i18n;
codec wire test + Chromium/WebKit e2e.

ui/src/screens/AccountDeleted.svelte

@@ -0,0 +1,53 @@
+<script lang="ts">
+  // The terminal account-deleted screen. While app.accountDeleted is set, App.svelte renders
+  // only this and all push/poll is stopped; the screen makes no network calls. Reopening the
+  // app just creates a fresh account. The Close button closes the host Mini App (Telegram /
+  // VK); a plain browser has nothing to close, so the button is hidden there.
+  import { closeDeletedApp } from '../lib/app.svelte';
+  import { insideTelegram } from '../lib/telegram';
+  import { insideVK } from '../lib/vk';
+  import { t } from '../lib/i18n/index.svelte';
+
+  const canClose = insideTelegram() || insideVK();
+</script>
+
+<div class="deleted">
+  <div class="card">
+    <h1>{t('deleted.title')}</h1>
+    <p class="msg">{t('deleted.body')}</p>
+    {#if canClose}
+      <button class="close" onclick={closeDeletedApp}>{t('common.close')}</button>
+    {/if}
+  </div>
+</div>
+
+<style>
+  .deleted {
+    height: 100%;
+    display: grid;
+    place-items: center;
+    padding: 24px;
+    background: var(--bg);
+  }
+  .card {
+    max-width: 28rem;
+    text-align: center;
+    color: var(--text);
+  }
+  h1 {
+    margin: 0 0 0.75rem;
+    font-size: 1.25rem;
+  }
+  .msg {
+    margin: 0;
+    color: var(--text-muted);
+  }
+  .close {
+    margin-top: 1.5rem;
+    padding: 10px 20px;
+    border: 1px solid var(--border);
+    background: var(--surface);
+    color: var(--text);
+    border-radius: var(--radius-sm);
+  }
+</style>