AudioService.init has no internal timeout and an unhandled
onConnectionSuspended case in its MediaBrowser self-bind; under bind
contention with the car's connection it can hang forever, so runApp
never ran (black car screen, white phone UI until process kill).
Race init against an 8s timeout without ever re-calling it: on timeout
run a bootstrap app that waits on the same future, wires the handler
exactly once when it resolves, reports errors via FlutterError, and
swaps to the real app. Auto browse sources now register before the
init await since they take no handler dependency.
