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/src/lib/telegram.ts

@@ -60,6 +60,27 @@ export function insideTelegram(): boolean {
 // 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';
 
+/**
+ * TelegramSdkOutcome records how the dynamic telegram-web-app.js load resolved, surfaced on the
+ * launch-error screen to tell the failure modes apart — notably 'error' / 'timeout', which mean the
+ * network could not reach telegram.org (the script blocked or hung):
+ *
+ *   not-attempted — loadTelegramSDK was never called (a plain web / native entry)
+ *   present       — window.Telegram.WebApp was already there (a cached load or native injection)
+ *   loaded        — the script loaded and defined window.Telegram.WebApp
+ *   no-webapp     — the script loaded (HTTP 200) but did not define window.Telegram.WebApp
+ *   error         — the script failed to load (telegram.org unreachable / blocked, a fast failure)
+ *   timeout       — the script neither loaded nor failed within the timeout (a blocked, hanging fetch)
+ */
+export type TelegramSdkOutcome = 'not-attempted' | 'present' | 'loaded' | 'no-webapp' | 'error' | 'timeout';
+
+let sdkLoadOutcome: TelegramSdkOutcome = 'not-attempted';
+
+/** telegramSdkOutcome returns how the last loadTelegramSDK attempt resolved (see TelegramSdkOutcome). */
+export function telegramSdkOutcome(): TelegramSdkOutcome {
+  return sdkLoadOutcome;
+}
+
 /**
  * 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
@@ -72,25 +93,29 @@ const sdkScriptSrc = 'https://telegram.org/js/telegram-web-app.js?62';
  */
 export function loadTelegramSDK(timeoutMs: number): Promise<boolean> {
   if (typeof document === 'undefined') return Promise.resolve(false);
-  if (webApp()) return Promise.resolve(true);
+  if (webApp()) {
+    sdkLoadOutcome = 'present';
+    return Promise.resolve(true);
+  }
   return new Promise<boolean>((resolve) => {
     let done = false;
-    const finish = (ok: boolean): void => {
+    const finish = (outcome: TelegramSdkOutcome): void => {
       if (done) return;
       done = true;
-      resolve(ok);
+      sdkLoadOutcome = outcome;
+      resolve(outcome === 'loaded');
     };
-    const timer = setTimeout(() => finish(!!webApp()), timeoutMs);
+    const timer = setTimeout(() => finish(webApp() ? 'loaded' : 'timeout'), timeoutMs);
     const s = document.createElement('script');
     s.src = sdkScriptSrc;
     s.async = true;
     s.onload = () => {
       clearTimeout(timer);
-      finish(!!webApp());
+      finish(webApp() ? 'loaded' : 'no-webapp');
     };
     s.onerror = () => {
       clearTimeout(timer);
-      finish(false);
+      finish('error');
     };
     document.head.appendChild(s);
   });
@@ -413,6 +438,9 @@ export interface TelegramDiag {
   hasSDK: boolean;
   /** Whether window.Telegram.WebApp is present. */
   hasWebApp: boolean;
+  /** How the dynamic telegram-web-app.js load resolved (see TelegramSdkOutcome) — 'error' /
+   *  'timeout' mean telegram.org was unreachable, the prime suspect for an empty launch. */
+  sdkLoad: TelegramSdkOutcome;
   /** Telegram's own platform string (ios | android | android_x | tdesktop | web | …), or ''. */
   platform: string;
   /** The Bot API version the client reports, or ''. */
@@ -454,6 +482,7 @@ export function collectTelegramDiag(): TelegramDiag {
   return {
     hasSDK: sdk,
     hasWebApp: !!w,
+    sdkLoad: sdkLoadOutcome,
     platform: w?.platform ?? '',
     version: w?.version ?? '',
     initDataLen: initData.length,