Shelly Wall Display XL: expose Motion RPC as motion binary sensor

## Enhancement Please add support for the Shelly Wall Display XL `motion:0` RPC component and expose its built-in radar motion detection as a Home Assistant motion binary sensor. Shelly added the `motion:0` RPC component for the Wall Display XL in firmware 2.6.0. The device reports its current motion state through `Motion.GetStatus`, including the `motion` boolean: ```json { "id": 0, "motion": true } ``` Please have the Shelly integration create an entity such as `binary_sensor.<device_name>_motion` with `device_class: motion`, mapping `motion: true` to on and `motion: false` to off. The goal is to expose the motion state already provided by the native Shelly RPC API without requiring a custom REST or MQTT implementation. ## Use cases The Wall Display XL already contains radar hardware capable of detecting motion. Exposing it through Home Assistant would allow the display to act as a room motion sensor for: - Triggering room lighting when motion is detected - Waking displays or dashboards when someone approaches - Triggering other room automations based on activity - Determining whether there has recently been movement in a room - Avoiding a separate motion sensor where a Wall Display XL is already installed ## Additional context - Shelly introduced the Motion RPC component for the Wall Display XL in firmware 2.6.0. - The relevant RPC component is `motion:0`, with state available through `Motion.GetStatus`. - Shelly firmware 2.7.2 included a fix related to registration of the radar's Motion RPC namespace, suggesting this is actively supported firmware functionality. - This request is specifically for exposing the existing motion state as a Home Assistant binary sensor. Configuration controls such as detection distance and blind time could be considered separately. Integration documentation: https://www.home-assistant.io/integrations/shelly/