Issue: after defaulting APNs delivery to production (#2381), development
builds installed from Xcode stopped receiving notifications entirely:
their sandbox device tokens were sent to the production APNs endpoint,
rejected as BadDeviceToken, and dropped as dead.
Fix: the iOS shell reads the aps-environment entitlement from the
embedded provisioning profile and exposes it to the web layer as a
document-start user script (added in capacitorDidLoad, since Capacitor
replaces the userContentController after webViewConfiguration(for:)).
Token registration reports the environment to the server, which stores
it per token and groups delivery by environment for both relay and
direct APNs sends. OPENCHAMBER_APNS_ENVIRONMENT remains as an explicit
override forcing every send to one environment.
TestFlight/App Store builds and older clients without the field default
to production, preserving released behavior; the relay already accepts
env per send request.