Per-client initital volume setting

[mill1000]

Is your feature request related to a problem? Please describe.

I have two Snapcast clients. Client A is connected to a traditional stereo with external volume control. Client B is directly connected to an amplifier and uses internal volume controls.

For day-to-day use, I have the volume on Client A set to 100%, and Client B is about 30%. I adjust the volume on Client B via Snapcast to my needs.

However, when my Snapcast server restarts (e.g. system reboots, Docker restarts), the volumes on both clients are reset to the initial volume setting. There is no setting that is good for both clients. 100% is too high for Client B, and 30% is too low for Client A.

Describe the solution you'd like
I'd like per-client initial volume settings. Either configured at the server, or perhaps snapclient can take an optional parameter to override the server setting.

Describe alternatives you've considered
Manually adjust the volumes on reset?

Additional context
N/A