- Fix millis() wraparound (49-day) in T1000SensorManager::loop() and
MicroNMEALocationProvider::loop() by switching from absolute comparison
(millis() > next_*) to elapsed-time arithmetic ((uint32_t)(millis() - last_*) >= interval)
with uint32_t timestamps; previous pattern could stall GPS updates and
time sync for up to ~24 days after wraparound
- Fix division-by-zero crash in get_heater_temperature() when ntc_volt == 0
(open circuit or bad ADC read); now returns 0.0f safely
- Fix out-of-bounds array access in get_heater_temperature(): loop exit at
i == 0 caused ntc_res2[i-1] / ntc_temp2[i-1] at index -1; loop exhaustion
at i == 136 caused ntc_res2[136] one-past-end read; clamped i to [1, 135]
with early-exit returns for edge temperatures and guarded interpolation
denominator against zero
