Splash only appears when the server is slow: no flash of the welcome screen on a fast start

The splash used to stay a fixed 700ms plus a fade, so a fast response still showed it
briefly and jumped away. Now only the matching background shows for the first 350ms;
the splash content appears only if the response has not arrived by then, and once shown
it stays at least 700ms. Not run on a device.

src/screens/SplashScreen.tsx

@@ -8,8 +8,12 @@ const GLYPHS = [
   { c: '÷', x: 64, d: 3.8 }, { c: '∑', x: 80, d: 0.6 }, { c: '×', x: 90, d: 4.6 },
 ];
 
-/** تا وقتی نشستِ قبلی بررسی می‌شود نمایش داده می‌شود؛ عمداً تأخیرِ ساختگی ندارد. */
-export function SplashScreen() {
+/**
+ * تا وقتی نشستِ قبلی بررسی می‌شود نمایش داده می‌شود. `showContent=false` فقط پس‌زمینه است؛ App
+ * محتوا را فقط وقتی روشن می‌کند که پاسخِ سرور دیر کرده باشد.
+ */
+export function SplashScreen({ showContent }: { showContent: boolean }) {
+  if (!showContent) return <div className="h-full bg-rose" />;
   return (
     <div className="relative flex h-full flex-col items-center justify-center overflow-hidden bg-rose">
       <div aria-hidden="true" className="pointer-events-none absolute inset-x-0 bottom-0 h-1/2">