iOS lane: SwiftUI shell, Rust xcframework, TestFlight in CI #2876

Part of #2875. The shared iOS groundwork every app below builds on. Plan: notes/STORES.md (branch office/sprocket-083a until its PR merges).

• apps/<app>/ios/: an Xcode project (or XcodeGen/Tuist spec, checked in as text) for a SwiftUI app, iPhone and iPad.
• scripts/ios/xcframework.ts: build an app's Rust crate for aarch64-apple-ios and aarch64-apple-ios-sim, generate Swift bindings with UniFFI, pack an .xcframework. Pilot on hippo_sim even though Park Hide & Seek ships first without one.
• A shared Swift package for the pieces every app needs: an edge client with protocol version handshake and an "Update to keep playing" screen, an offline screen, eqosys sign-in via ASWebAuthenticationSession.
• CI: an ios-drop job (or a lane in desktop-drop.yml) on a macOS runner in the drops environment. A -beta.N tag uploads to TestFlight; a stable tag submits for review. Uses the App Store Connect API key from the MANUAL RUN issue; agents never see it.
• Versions: CFBundleShortVersionString from the tag, build number from the run number.

Done when a dry run builds an unsigned .ipa for one app in CI.