Fix XHS2-UE battery voltage curve

[klinquist]

Summary

Fixes #12608.

This updates the Universal Electronics Inc XHS2-UE / URC4460BC0-X-R contact sensor battery curve to derive percentage from measured voltage:

• changes voltageToPercentage from 3V_2100 to {min: 2500, max: 2800}
• adds a regression test that 2800mV reports 100% even when the device reports a stale 27%

Why

This is the same behavior fixed for the Sylvania 74388 contact sensor in #12486: after a fresh battery change, the device can report a healthy/full voltage while also reporting a stale low battery percentage.

For XHS2-UE, the observed state was:

{
    "battery": 27,
    "battery_low": false,
    "contact": true,
    "linkquality": 188,
    "tamper": false,
    "temperature": 20,
    "voltage": 2800
}

Using {min: 2500, max: 2800} matches the previously merged Sylvania fix and treats 2800mV as full.

Tests

• pnpm exec vitest run --config ./test/vitest.config.mts test/fromZigbee.test.ts
• pnpm run check
• commit hook: pnpm run build
• commit hook: pnpm run check
• commit hook: pnpm test

[Koenkk]

Could you fix the merge conflict?

[klinquist]

Thanks for the heads up. I rebased the branch on the latest upstream master and resolved the merge conflict.

[Koenkk]

Thanks!