fix(ui): load telegram-web-app.js dynamically with a timeout

The Telegram SDK was a render-blocking <script src="telegram.org/..."> in the
shared index.html shell, so it ran on every entry (/telegram/, /app/, native).
On a network that blocks telegram.org — common where Telegram itself reaches
users only over a proxy — the script hangs forever, stranding the whole page,
including the launch-diagnostic screen meant to surface exactly this failure.
This is the likely root cause of the Android "won't open" reports (all launch
methods fail identically; iOS on a different network works).

Remove the head <script> and load the SDK dynamically (lib/telegram.ts
loadTelegramSDK) with a 10s timeout, only on a Telegram entry (the /telegram/
path or a tgWebApp launch fragment). The SPA — served from our own reachable
origin — boots first and controls the load: on a block/error it falls through
to the diagnostic screen (reporting sdk: no) instead of hanging, and Retry
re-attempts. /app/ and the native build no longer touch telegram.org.

Pin the SDK to the version the official page recommends (?62) for the newer
client features the app already uses (fullscreen, safe areas, swipe guard).

Tests: loadTelegramSDK unit tests (present / error / timeout); an e2e that
aborts the script fetch and asserts the diagnostic still renders.

ui/src/lib/telegram.ts

@@ -1,6 +1,7 @@
-// Telegram Mini App SDK access. The official telegram-web-app.js (loaded in
-// index.html) exposes window.Telegram.WebApp; this wraps the subset the app uses:
-// launch detection, initData (for auth.telegram), the deep-link start parameter,
+// Telegram Mini App SDK access. The official telegram-web-app.js (loaded dynamically with a
+// timeout by loadTelegramSDK — not a render-blocking <script> in index.html, so a network that
+// blocks telegram.org cannot hang the page) exposes window.Telegram.WebApp; this wraps the subset
+// the app uses: launch detection, initData (for auth.telegram), the deep-link start parameter,
 // theme params, and ready()/expand(). Every helper is safe to call outside Telegram.
 
 import type { TelegramThemeParams } from './theme';
@@ -54,6 +55,47 @@ export function insideTelegram(): boolean {
   return !!w && typeof w.initData === 'string' && w.initData.length > 0;
 }
 
+// The ?NN suffix pins the Bot API SDK version Telegram serves (and busts the cache); keep it at the
+// version the official Mini Apps page currently recommends so newer client features (fullscreen,
+// safe-area insets, vertical-swipe guard, …) are available. Bump it when Telegram bumps theirs.
+const sdkScriptSrc = 'https://telegram.org/js/telegram-web-app.js?62';
+
+/**
+ * loadTelegramSDK injects the official telegram-web-app.js and resolves true once
+ * window.Telegram.WebApp is available, or false if the script errors or does not load within
+ * timeoutMs. It is loaded dynamically — not a render-blocking <script> in index.html — so a network
+ * that blocks telegram.org (common where Telegram itself reaches users only over a proxy) cannot
+ * hang the page and strand the app or the launch-error screen. Resolves true immediately when the
+ * SDK is already present (a cached load, or a future native injection); a fast connection failure
+ * resolves via the error event without waiting out the timeout, so the timeout only bounds a true
+ * hang.
+ */
+export function loadTelegramSDK(timeoutMs: number): Promise<boolean> {
+  if (typeof document === 'undefined') return Promise.resolve(false);
+  if (webApp()) return Promise.resolve(true);
+  return new Promise<boolean>((resolve) => {
+    let done = false;
+    const finish = (ok: boolean): void => {
+      if (done) return;
+      done = true;
+      resolve(ok);
+    };
+    const timer = setTimeout(() => finish(!!webApp()), timeoutMs);
+    const s = document.createElement('script');
+    s.src = sdkScriptSrc;
+    s.async = true;
+    s.onload = () => {
+      clearTimeout(timer);
+      finish(!!webApp());
+    };
+    s.onerror = () => {
+      clearTimeout(timer);
+      finish(false);
+    };
+    document.head.appendChild(s);
+  });
+}
+
 /**
  * telegramOpenLink opens a t.me link through the Mini App SDK, so Telegram navigates to
  * it natively (e.g. a bot chat) rather than spawning an in-app browser tab. Returns false
@@ -303,6 +345,14 @@ export function onTelegramPath(): boolean {
   return location.pathname.startsWith('/telegram/');
 }
 
+/** hasLaunchFragment reports whether the URL fragment carries Telegram launch params (tgWebApp…),
+ *  the form Telegram appends when opening a Mini App — so the SDK is loaded for a Mini App opened
+ *  at the site root too, not only the /telegram/ path. */
+export function hasLaunchFragment(): boolean {
+  if (typeof location === 'undefined') return false;
+  return location.hash.includes('tgWebApp');
+}
+
 // --- Launch diagnostics (the /telegram/ entry without sign-in data) ---
 
 /** The initData fields a valid Telegram launch is expected to carry; their absence is the signal