feat(telegram): native dialogs for confirms and deep-link notices

Inside the Mini App, route the destructive confirmations (resign, block, unfriend)
through Telegram's native showConfirm, and present the deep-link info modals (stale
invite, welcome-on-redeem) as a native showPopup whose button opens the bot chat.
Outside Telegram, or on a client predating the dialogs, the existing in-app Modal is
used unchanged; offline also keeps the modal so the action retains its disabled state.

Adds showConfirm/showPopup wrappers to telegram.ts and a pure popup-params builder
(nativedialogs.ts) with unit tests; the deep-link modal components choose native vs
in-app via an effect gated on insideTelegram + dialog availability.

ui/src/game/Game.svelte

@@ -24,7 +24,7 @@
   import { getCachedGame, setCachedGame, setCachedDraft, type CachedGame } from '../lib/gamecache';
   import { patchLobbyGame } from '../lib/lobbycache';
   import { applyGameOver, applyMoveDelta, applyOpponentJoined, type DeltaResult } from '../lib/gamedelta';
-  import { telegramHaptic } from '../lib/telegram';
+  import { insideTelegram, telegramDialogsAvailable, telegramHaptic, telegramShowConfirm } from '../lib/telegram';
   import {
     BLANK,
     newPlacement,
@@ -712,6 +712,16 @@
       busy = false;
     }
   }
+  // onResignClick: inside the Mini App (and online) confirm with Telegram's native dialog and resign
+  // on accept; otherwise open the in-app confirm modal (which also carries the offline-disabled action).
+  async function onResignClick(): Promise<void> {
+    if (connection.online && insideTelegram() && telegramDialogsAvailable()) {
+      if (await telegramShowConfirm(t('game.confirmResign'))) doResign();
+      return;
+    }
+    resignOpen = true;
+  }
+
   async function doResign() {
     resignOpen = false;
     busy = true;
@@ -1149,7 +1159,7 @@
           <button class="hicon" onclick={exportGcg} aria-label={t('game.exportGcg')}>📤</button>
         {/if}
       {:else}
-        <button class="hicon" onclick={() => (resignOpen = true)} disabled={waitingForOpponent} aria-label={t('game.dropGame')}>🏁</button>
+        <button class="hicon" onclick={onResignClick} disabled={waitingForOpponent} aria-label={t('game.dropGame')}>🏁</button>
       {/if}
       {#if !view.game.multipleWordsPerTurn}<span class="oneword-label">{t('game.oneWordRule')}</span>{/if}
       <!-- A finished AI game has no comms at all (no chat, and the dictionary closes with the