[Darwin48V] Update fan_service to control fan leds

[aalamsi22]

Pre-submission checklist

• I've ran the linters locally and fixed lint errors related to the files I modified in this PR. You can install the linters by running pip install -r requirements-dev.txt && pre-commit install
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Summary

Updates the fan_service to control leds. Add rpmMin to fan configs for immediate fan failure detection.

Without rpmMin, fan_service relies solely on the 300s kFanFailThresholdInSec timeout to detect fan failure. When a fan is removed, fanRpm defaults to 0 but fanFailed stays false until 5minutes of continuous access failures elapse — leaving the LED green the entire time.

Adding rpmMin=2400 enables the immediate rpmMin check in ControlLogic.cpp: fanRpm (0) < rpmMin (2400) triggers fanFailed=true on the very next control loop cycle, bypassing the 300s delay.

The value 2400 is ~10% below the hardware minimum RPM floor of 2739, measured on rkd340 at PWM=0. This also catches degraded fans that can't maintain the CPLD's minimum speed.

Test Plan

fan_service_hw_test PASSES
fan leds update correctly on fan insertion/removal

[meta-codesync]

@joancaneus has imported this pull request. If you are a Meta employee, you can view this in D108456338.