[Feature Request] Provide VPD sensor to the system

[BubiBalboa]

I'd love to have the current VPD value available in other parts of HA to use in alerts and automations.

I think it makes sense for this integration to be the one "VPD provider" for the system. I assume this would be done by exposing the VPD value the chart uses as a sensor.

It's easy enough to create a helper that acts as a VPD sensor but it's not exactly ideal to have the system calculate the same value twice. I had it happen that something changed and the VPD chart and the helper sensor didn't match anymore. Makes troubleshooting more complicated. That's why it would be nice to have just one VPD value in the system, provided by this integration.

Thank you for creating this software. Super useful.