Biomekka 1.8.43 - HEATWAVE TRICKLE+MIST

Emergency heatwave cooling update:
- Keeps 1.8.42 heatwave fan ramp, heater lockout, and LED/COB blackout above 28.0C.
- Adds an aggressive evaporative cooling stage from 28.0C with 27.5C release hysteresis.
- Heatwave cooling cycle is 60 seconds total:
  - trickle ON for 10 seconds
  - mist ON for 10 seconds immediately after trickle stops
  - 40 seconds clear-air/exhaust time
- Normal trickle remains 5 seconds every 3 minutes when not in heatwave cooling mode.
- Mist pulse is skipped/stopped if humidity is 92%+ or if door/spray/rain/storm conflicts appear.
- No new Grafana fields are used for this mode.