feat: add ATF temp

[BoYanZh]

Tested and verified on a 2025 GR86 6AT. This CAN ID appears to be AT-exclusive.

Validation Summary:

1. Stall Test: Holding brake in D with throttle produces a real-time temperature spike after a 2-4s thermal propagation delay.
2. Cooling Rate: Engine-off cooling curve matches the thermal inertia of the transmission assembly.
3. Cold Start Alignment: Adjusted the offset to -50, which perfectly matches ambient air and coolant temperatures during cold starts.
4. Community Cross-Verification: Aligns with independent data from Chinese platform developer '6mb', who noted a 10°C downward variance from the generic -40 standard formulas, confirming the mathematical validity of our -50 adjustment.

Submitting as an RFC for other Gen2 AT data loggers to cross-verify.