Park Hide & Seek on iOS: store build calls the edge, with a real store link #2903

Part of #2875. Focus app and platform: Park Hide & Seek on iOS first.

• Replace the placeholder STORE_URL in apps/park-hide-seek/src/api.ts with the App Store listing once it exists (MANUAL RUN if it needs the owner).
• Check the iOS build sends pv on /ws and /api and shows the "Update to keep playing" text with a tappable link (Edge protocol versions: old store builds are asked to update (Part of #2875) #2900 / Edge protocol versions: old store builds keep working or ask to update #2878).
• Keep the stage the build calls out of cost sweeps (COSTS.md, done in Edge protocol versions: old store builds are asked to update (Part of #2875) #2900).

Platform knowledge shared with other apps lives in the package from the sibling issue, not here.