Smooth screen transitions: new screen waits hidden until its data arrives, no half-built flash

- Navigator stage: the next screen mounts hidden under the current one and is revealed only when its
  first data has arrived (ScreenGate held by useAsync/useGateHold), at most 450 ms; a thin top bar shows
  after 120 ms of waiting. Push slides from the left, back from the right, tabs only fade.
- Session cache (stale-while-revalidate) for screen GETs: revisited screens draw instantly.
- Home map and stats are fetched during the splash, so the first screen arrives complete.
- Entrance pop-ins (mascot, islands, lesson cards) run on first view only, not on every revisit.
- Shop status card shows placeholders instead of a wrong «نداری» while loading.
- Re-tapping the open tab scrolls to top instead of reloading; sheets close with a swipe down.
- Quiz: «۱ از ۴» instead of «۱/۴» (read as a fraction), varied praise, «N تا پشتِ هم درست»,
  growth-mindset copy after a weak round, zero-reward tiles hidden.
- Streak: a concrete next step when the streak is 0 or today is still empty.

Checked in headless Chrome against the local backend (frame captures at 150 ms and 700 ms latency,
rapid tab tapping, full quiz run). Not checked on a real phone or iOS Safari.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

src/state/AppData.tsx

@@ -27,18 +27,26 @@ interface AppData {
 
 const AppDataContext = createContext<AppData | null>(null);
 
+/** آنچه در اسپلش پیش از ورود به اپ گرفته شد (App.prefetchMain). */
+export interface Prefetch {
+  home: HomeResponse | null;
+  summary: UserSummary | null;
+}
+
 export function AppDataProvider({
   initialProfile,
   grades,
+  prefetch,
   children,
 }: {
   initialProfile: UserProfile;
   grades: Grade[];
+  prefetch?: Prefetch;
   children: ReactNode;
 }) {
   const [profile, setProfile] = useState(initialProfile);
-  const [summary, setSummary] = useState<UserSummary | null>(null);
-  const [home, setHome] = useState<HomeResponse | null>(null);
+  const [summary, setSummary] = useState<UserSummary | null>(prefetch?.summary ?? null);
+  const [home, setHome] = useState<HomeResponse | null>(prefetch?.home ?? null);
   const [homeError, setHomeError] = useState<unknown>(null);
   const [companion, setCompanionChar] = useState<SeyarChar>('sigma');
   const [unreadCount, setUnreadCount] = useState(0);
@@ -69,8 +77,9 @@ export function AppDataProvider({
   }, []);
 
   useEffect(() => {
-    void refreshHome();
-    void refreshSummary();
+    // آنچه در اسپلش رسیده دوباره گرفته نمی‌شود؛ فقط کم‌ها.
+    if (!prefetch?.home) void refreshHome();
+    if (!prefetch?.summary) void refreshSummary();
     void refreshUnread();
     api.characters
       .list()
@@ -79,6 +88,8 @@ export function AppDataProvider({
         if (selected) setCompanionChar(selected);
       })
       .catch(() => {});
+    // فقط بارِ اول؛ prefetch بعد از mount عوض نمی‌شود.
+    // eslint-disable-next-line react-hooks/exhaustive-deps
   }, [refreshHome, refreshSummary, refreshUnread]);
 
   const value = useMemo<AppData>(