fix: read the G Pro X Wireless battery through G Hub's own curves (#1)

[manuelmayer-dev]

What does this PR do?

HeadsetControl's G Pro points read 3924 mV as 65% while G Hub showed 79%, and any charging voltage as 100% while G Hub showed 87%. G Hub ships a power model for the 0ABA (pro_x_wireless_headset_battery.xml) with a discharge curve and a charge curve; the headset now reads through points sampled from both.

The charge curve rises to about 4275 mV at 87%, then falls while the battery fills to 100%, so a charge is followed per device path: the turn is a drop of 5 mV below the peak, and the reading never goes down during one charge.

The hardware test that prints the raw voltage now covers the headset too.

Checklist

• I have read AGENTS.md and CONTRIBUTING.md.
• dotnet build and dotnet test pass locally.
• I updated README.md / AGENTS.md if this changes what they describe.
• If this touches a device backend: I tested it against the real hardware (say which model/OS
  below). If you could not, say so explicitly rather than presenting it as tested.

Device/hardware tested against (if applicable)

Logitech Pro X Wireless, Windows 11, Wired/Wireless

AI assistance

Assisted by Claude Code (Opus 5.5)