Status LED Quiet Mode

[eMadman]

Goal: Stop blue LED blinking after a period of inactivity.

works with the rebootTimer in maintenanceLoop()

Blue LED will be on for 15 minutes after a reboot or device connection.

Tested on desk:

1. Normal power-on, idle: LED blinks/solid for 15 min, then goes dark.
2. Active ride: Any HR/watts/incline change resets the 15-min window; LED stays on throughout the session.
3. Rider stops: LED goes dark 15 minutes after the last activity change
4. Inactivity reboots - LED stays off after 30 minutes
5. BLE Client connection - LED lights up after client connection
6. Manual reboot - LED on for 15 minutes
7. Power Cycle - LED on for 15 minutes
8. Firmware downgrade LED behavior is normal after flashing back to develop.