com.apple.developer.devicecheck.appattest-environment was hardcoded to
"development" for every build, including the App Store/TestFlight
distribution build. Apple's App Attest servers validate this claim
against how the app was actually signed/distributed, so a "development"
claim on a real distribution build fails - guest session handshake
never gets past the challenge step, no store/city data ever loads.
Parameterized per configuration: development for Debug, production for
Release, via an APP_ATTEST_ENVIRONMENT build setting.
Adds a pre-login public store locator (guest session via DeviceCheck/App
Attest, keychain-backed token storage) so the app no longer forces sign-in
before showing any content, plus updated support URL metadata.
