Stream fixes with FusedLocationProvider

The same FusedLocationProviderClient, running inside the service

Module 11 called FusedLocationProviderClient.requestLocationUpdates from a ViewModel, tied to whatever screen was on top. Here the exact same API runs inside the foreground service instead — the fixes keep flowing no matter what's on screen, because the service, not the screen, owns the subscription.

A LocationRequest still configures the stream: Priority.PRIORITY_HIGH_ACCURACY for the best fix the device can produce, and an interval in milliseconds for how often to check. Ties back to module 13's callbackFlow — wrapping requestLocationUpdates's callback-based API in a callbackFlow turns fixes into a Flow<Location> the rest of the service (and eventually the socket-publish code from module 11) can collect like any other stream.