DEFAULT_SETTLE_DELAY
Delay applied before every connection attempt (including the first) so the BLE stack and the firmware-side GATT session have time to settle.
Empirically validated against the meshtastic-client KMP SDK probes (Apr 2026): with a 1.5 s pause between disconnect→reconnect cycles, 3/5–4/5 attempts failed mid-handshake (Stage1Draining timeouts) because the firmware had not yet released its GATT session from the previous cycle. With ≥ 5 s pause, success rate rose to 5/5 against a strong (-53 dBm) link. 3 s is a conservative compromise on Android, whose BLE stack is more mature than btleplug+CoreBluetooth, but the firmware-side cleanup constraint is the same.