Earlier I over-corrected: 'don't scan when the strap is absent' became
'never auto-connect'. Restore conditional auto: at recording start (ride or
workout) connect the paired strap and poll; absent strap is safe now
(BleHrService scans briefly and stops - no drain). No paired strap -> HR off.
- gps.js: GPS.setHrOn(on) - connect+poll / disconnect+stop; start auto-ons it.
- Record screen: the inconvenient 'Ветер' button is gone; in its place an
HR on/off toggle (square, heart+pulse icon; grey off, red on) -> setHrOn.
(Also corrected a stale assumption: the phone DOES have Google services.)