feat(ui): record the SDK load outcome in the launch diagnostic

The diagnostic showed only sdk: yes/no (window.Telegram presence), not why the
SDK was absent. Capture how the dynamic telegram-web-app.js load resolved —
present / loaded / no-webapp / error / timeout — and surface it as
"sdk-load: <outcome>". error/timeout pinpoint a blocked or hanging telegram.org
(the prime suspect for an empty launch); no-webapp a loaded-but-broken script.

loadTelegramSDK records the outcome (telegramSdkOutcome); collectTelegramDiag
carries it into the screen. Unit tests cover each outcome; the blocked-script
e2e now asserts sdk-load: error.

ui/e2e/telegram.spec.ts

@@ -131,5 +131,6 @@ test('a blocked telegram-web-app.js does not hang the diagnostic screen', async
   await page.goto('/telegram/');
 
   await expect(page.getByRole('button', { name: 'Share' })).toBeVisible();
-  await expect(page.getByText('sdk: no')).toBeVisible();
+  // The diagnostic names the load outcome: a failed fetch reads as sdk-load: error.
+  await expect(page.getByText('sdk-load: error')).toBeVisible();
 });