Add checks.battery-charge-limit (runNixOSTest): the test_power module
fakes a Mains adapter, toggling ac_online emits a real power_supply
uevent, and the test asserts the udev rule restarts the oneshot (changed
InvocationID). Verifies the re-apply *trigger* at runtime, beyond the
earlier eval check; the sysfs write still needs real hardware. Also
records the SSH_AUTH_SOCK rendered-artifact verification in the roadmap.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>