Adds the `zha` extra component so Home Assistant can drive the
Nabu Casa Connect ZBT-2 radio, and puts the `hass` service user in
`dialout` so it can open `/dev/serial/by-id/usb-Nabu_Casa_..._ZBT-2_*`.
Pairing is then handled through the standard ZHA wizard in the HA UI.
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>