Tie GPS tracking to trip status and reconcile it after loading trips

GPS tracking is a side effect of the trip lifecycle, not a prerequisite for displaying trips.

• Start tracking only when a trip enters inTransit.
• Do not start tracking for boarding or other non-transit states.
• Stop tracking when a trip becomes completed or returns to scheduled, clearing the stored vehicle identifier.
• When trips are loaded, inspect the complete trip list for an already-inTransit trip and start tracking if tracking is not already running. Prefer the selected trip when it is active; otherwise use an active trip from the loaded list.
• Guard startup reconciliation so it runs once per page initialization, and make starting idempotent when tracking is already active.
• If the tracking controller is unavailable, continue rendering and updating trips without crashing.

This keeps persisted trip state and process state convergent after app restarts while preserving trip-list availability when tracking services are unavailable.