feat: add fullscreen QR code for subscription connection

- New ConnectionQR page with fullscreen QR display (no modal)
- QR button in InstallationGuide header next to platform selector
- Respects hideLink setting: shows URL below QR only when visible
- i18n translations for ru, en, zh, fa

src/pages/Connection.tsx

@@ -35,6 +35,15 @@ export default function Connection() {
     navigate(-1);
   }, [navigate]);
 
+  const handleOpenQR = useCallback(() => {
+    navigate('/connection/qr', {
+      state: {
+        url: appConfig?.subscriptionUrl,
+        hideLink: appConfig?.hideLink ?? false,
+      },
+    });
+  }, [navigate, appConfig?.subscriptionUrl, appConfig?.hideLink]);
+
   useEffect(() => {
     const handleKeyDown = (e: KeyboardEvent) => {
       if (e.key === 'Escape') {
@@ -184,6 +193,7 @@ export default function Connection() {
       onOpenDeepLink={openDeepLink}
       isTelegramWebApp={isTelegramWebApp}
       onGoBack={handleGoBack}
+      onOpenQR={handleOpenQR}
     />
   );
 }