Biomekka 1.8.22

TODO item completed: storm lighting ramp behaviour.

Changes:
- Daytime pre-storm now ramps lighting down across the full 15-minute pre-storm build-up.
- Pre-storm ramp affects both RGB storm atmosphere and COB target PWM.
- Daytime storm now enters full storm lighting immediately after the pre-storm ramp, instead of doing a separate sudden storm dim.
- Daytime post-storm now ramps lighting back to normal over 15 minutes.
- Night/dusk storms do not darken the habitat; they keep the existing moody/night lighting and add lightning only.
- Manual storm stop cancels recovery ramp, so "storm off" behaves like an immediate stop.

Files changed:
- lighting.cpp
- lighting.h
- biomekka_1_8_22.ino

No changes made to:
- pins
- Goblin command mapping
- relays
- sensor addresses
- telemetry schema
- MQTT topics
- storm eligibility logic
- pre-storm humidity timing
- dashboard layout