feat(a11y,i18n): more modal focus-traps + Telegram theme/language sync

Modal a11y:
- focus-trap + role=dialog/aria-modal/aria-labelledby on AdminRoles delete confirm
  and AdminBanSystem user-detail modal (+ close aria-label)

Telegram theme/language sync (first run only, explicit choice always wins):
- getTelegramColorScheme() / getTelegramLanguageCode() helpers in useTelegramSDK
- useTheme initial state follows the Telegram client color scheme when no stored theme
- applyTelegramLanguage() adopts the Telegram client language when no stored choice,
  called from main.tsx after SDK init (launch params unavailable before init)

src/main.tsx

@@ -24,7 +24,7 @@ import { AppWithNavigator } from './AppWithNavigator';
 import { ErrorBoundary } from './components/ErrorBoundary';
 import { initLogoPreload } from './api/branding';
 import { getCachedFullscreenEnabled, isTelegramMobile } from './hooks/useTelegramSDK';
-import './i18n';
+import { applyTelegramLanguage } from './i18n';
 import './styles/globals.css';
 
 // Polyfill Object.hasOwn for older iOS/Android WebViews (Safari < 15.4, old Chrome).
@@ -55,6 +55,9 @@ if (isTelegramEnv && !alreadyInitialized) {
 
     clearStaleSessionIfNeeded(retrieveRawInitData() || null);
 
+    // Adopt the user's Telegram client language on first run (no explicit choice yet).
+    applyTelegramLanguage();
+
     // Each mount in its own try/catch so one failure doesn't block others.
     // mountMiniApp() internally mounts themeParams in SDK v3,
     // so we don't call mountThemeParams() separately to avoid ConcurrentCallError.