Pin mapping verified against HTIT-Tracker V0.5 schematic:
- GPIO35 (GPS_EN): N-ch MOSFET drives P-ch high-side switch, active HIGH
- GPIO36 (GPS_RST): hardware reset, active LOW
- GPIO33/34: UART TX/RX
Delegates power management to MicroNMEALocationProvider begin()/stop()
which independently controls GPS power via GPS_EN and shares VEXT with
the display through RefCountedDigitalPin.
