fix(game): own export chooser modal; PNG option outside in-app webviews only

Telegram's native showPopup delivers its callback with no user
activation, so navigator.share (TG iOS) and clipboard writes (TG
Android GCG copy) silently fail from it — the chooser is now always the
app's own modal, keeping the button click's gesture alive for the
delivery APIs.

The data:URL preview modal is dropped: the Android TG/VK long-press
menu mangles data: URLs (dead download, black-screen open, base64
clipboard garbage), so a binary PNG has no working client-side route in
those webviews at all. The image option is withheld there until the
server-rendered signed-URL delivery (Telegram downloadFile /
VKWebAppDownloadFile) lands; the plain web and mobile browsers keep it.

On-device findings by the owner on the test contour (TG iOS, TG
Android, VK Android).

ui/src/game/Game.svelte

@@ -22,12 +22,12 @@
   import { variantNameKey, usesStarBlank, BLANK_STAR } from '../lib/variants';
   import { alphabetLetters, hasAlphabet } from '../lib/alphabet';
   import { hintsLeft } from '../lib/hints';
-  import { blobToDataURL, canCopyImage, copyImageToClipboard, shareOrDownloadGcg, shareOrDownloadImage } from '../lib/share';
+  import { shareOrDownloadGcg, shareOrDownloadImage } from '../lib/share';
   import { insideVK, vkCopyText } from '../lib/vk';
   import { getCachedGame, setCachedGame, setCachedDraft, type CachedGame } from '../lib/gamecache';
   import { patchLobbyGame } from '../lib/lobbycache';
   import { applyGameOver, applyMoveDelta, applyOpponentJoined, type DeltaResult } from '../lib/gamedelta';
-  import { insideTelegram, telegramDialogsAvailable, telegramShowConfirm, telegramShowPopup } from '../lib/telegram';
+  import { insideTelegram, telegramDialogsAvailable, telegramShowConfirm } from '../lib/telegram';
   import { haptic } from '../lib/haptics';
   import {
     BLANK,
@@ -928,26 +928,18 @@
   }
 
   // The finished-game export offers two formats — the GCG file and the rendered PNG image —
-  // behind one 📤 button: a native Telegram popup where available, the app's own modal
-  // elsewhere (the onResignClick pattern).
+  // behind one 📤 button, always through the app's own modal. Never Telegram's native popup
+  // here: its callback runs with NO user activation, so navigator.share / clipboard writes
+  // silently fail from it (verified on-device, TG iOS + Android). A real DOM button click in
+  // the modal keeps the gesture alive for the delivery APIs.
   let exportOpen = $state(false);
-  let exportPreviewUrl = $state('');
-  let exportBlob: Blob | null = null;
+  // The PNG option is withheld in an in-app WebView (Telegram / VK) for now: a binary image
+  // has no working delivery there (no Web Share, a dead <a download>, text-only clipboard,
+  // and the long-press menu mangles data: URLs). It returns with the server-rendered
+  // signed-URL delivery (Telegram downloadFile / VKWebAppDownloadFile).
+  const exportImageAvailable = $derived(!(insideTelegram() || insideVK()));
 
-  async function onExportClick() {
-    if (insideTelegram() && telegramDialogsAvailable()) {
-      const choice = await telegramShowPopup({
-        message: t('game.exportChoice'),
-        buttons: [
-          { id: 'image', type: 'default', text: t('game.exportImageOpt') },
-          { id: 'gcg', type: 'default', text: t('game.exportGcgOpt') },
-          { type: 'cancel' },
-        ],
-      });
-      if (choice === 'image') void exportImage();
-      else if (choice === 'gcg') void exportGcg();
-      return;
-    }
+  function onExportClick() {
     exportOpen = true;
   }
 
@@ -963,38 +955,21 @@
   }
 
   // exportImage renders the finished game as a PNG (lib/gameimage, dynamically imported so the
-  // renderer stays out of the startup bundle) and delivers it: Web Share / download where they
-  // work, else the preview modal (Android Telegram/VK WebView and the desktop VK iframe, where
-  // neither exists for a binary file) with a long-press/right-click save hint.
+  // renderer stays out of the startup bundle) and delivers it — Web Share where the platform
+  // supports it, else a download (only reachable outside the in-app WebViews, see
+  // exportImageAvailable).
   async function exportImage() {
     if (!view) return;
     try {
       const { renderGameImage } = await import('../lib/gameimage');
       const blob = await renderGameImage(view.game, moves, { actionLabel: moveActionLabel });
       const file = new File([blob], `game-${id.slice(0, 8)}.png`, { type: 'image/png' });
-      const outcome = await shareOrDownloadImage(file, insideTelegram() || insideVK());
-      if (outcome === 'preview') {
-        exportBlob = blob;
-        exportPreviewUrl = await blobToDataURL(blob);
-      }
+      await shareOrDownloadImage(file);
     } catch (e) {
       handleError(e);
     }
   }
 
-  function closeExportPreview() {
-    exportPreviewUrl = '';
-    exportBlob = null;
-  }
-
-  async function copyExportImage() {
-    if (exportBlob && (await copyImageToClipboard(exportBlob))) {
-      showToast(t('game.imageCopied'), 'info');
-    } else {
-      showToast(t('error.generic'), 'error');
-    }
-  }
-
   // The GCG export copies to the clipboard in an Android in-app WebView (no Web Share, a dead
   // <a download>): VKWebAppCopyText inside VK — which also works in the desktop VK iframe, where
   // navigator.clipboard is blocked — and navigator.clipboard elsewhere.
@@ -1512,11 +1487,13 @@
 {#if exportOpen}
   <Modal title={t('game.exportGcg')} onclose={() => (exportOpen = false)}>
     <div class="export-opts">
-      <button class="confirm" onclick={() => { exportOpen = false; void exportImage(); }}>
-        {t('game.exportImageOpt')}
-      </button>
+      {#if exportImageAvailable}
+        <button class="confirm" onclick={() => { exportOpen = false; void exportImage(); }}>
+          {t('game.exportImageOpt')}
+        </button>
+      {/if}
       <button
-        class="export-alt"
+        class={exportImageAvailable ? 'export-alt' : 'confirm'}
         onclick={() => { exportOpen = false; void exportGcg(); }}
         disabled={!connection.online}
       >
@@ -1526,16 +1503,6 @@
   </Modal>
 {/if}
 
-{#if exportPreviewUrl}
-  <Modal title={t('game.exportImageOpt')} onclose={closeExportPreview}>
-    <img class="export-preview" src={exportPreviewUrl} alt={t('game.exportGcg')} />
-    <p class="export-hint">{t('game.imageSaveHint')}</p>
-    {#if canCopyImage()}
-      <button class="confirm" onclick={copyExportImage}>{t('game.imageCopy')}</button>
-    {/if}
-  </Modal>
-{/if}
-
 <style>
   .scoreboard {
     position: relative;
@@ -1939,19 +1906,6 @@
   .export-alt:disabled {
     opacity: 0.5;
   }
-  /* Preview modal (webviews with no Web Share / download): the image itself is the artifact —
-     the user saves it with a long-press (or right-click in the desktop VK iframe). */
-  .export-preview {
-    display: block;
-    width: 100%;
-    border: 1px solid var(--border);
-    border-radius: var(--radius-sm);
-  }
-  .export-hint {
-    margin: 8px 0;
-    color: var(--text-muted);
-    font-size: 0.85rem;
-  }
 
   /* --- Landscape (wide) layout ------------------------------------------------------------
      When the viewport is wider than tall the game lays out as two columns: a left panel (rack,