Precipitation intensity / volumetric flux units aren't auto-converted between metric and US customary

Precipitation intensity / volumetric flux units aren't auto-converted between metric and US customary: a task in MiMo-V2.6-RL-harbor-code: MiMo-V2.6-RL Code (Harbor) (Harbor dataset). I have a couple of weather-related sensors that report rain rate. Depending on the integration they expose device…

The task

I have a couple of weather-related sensors that report rain rate. Depending on the integration they expose `device_class: precipitation_intensity` (or `speed`) with a unit like `mm/h`, `mm/d`, `in/h` or `in/d` (the `UnitOfVolumetricFlux` units).

Part of FineEnvs/MiMo-V2.6-RL-harbor-code.