[Device]: Logitech MX Ergo trackball (Unifying receiver)

### Pre-flight checklist

- [x] I quit **Logi Options+** before testing.
- [x] I searched existing issues for my device.

### Device model

Logitech MX Ergo trackball (the original, not the MX Ergo S / Ergo M575)

### Connection

Unifying receiver

### What's the problem?

Device is not detected at all

### `openlogi list` output

```text
No output since: https://github.com/AprilNEA/OpenLogi/pull/362
```

### `openlogi diag features` output

```text
No output since: https://github.com/AprilNEA/OpenLogi/pull/362
```

### Details

### What I'm asking for

Support for the MX Ergo trackball. It is a HID++ device on a Unifying
receiver, so I'd expect at least button remapping, DPI control, and
per-app profiles to be feasible — SmartShift does not apply (no
MagSpeed wheel), but the trackball has a dedicated precision-mode
button and two thumb buttons (Back/Forward) that would be great to
remap.

### Current behavior

```
$ openlogi list

```

### HID++ diagnostics

```
$ openlogi diag features

```

### OpenLogi Diagnostics

### Additional notes

- Buttons: left, right, middle (wheel click), Back, Forward, precision-mode
(DPI toggle), Easy-Switch (channel 1/2); scroll wheel with left/right tilt.
- Happy to test dev builds and provide further dumps or captures — I use
this device daily over the Unifying receiver.

Start by running `openlogi list` and `openlogi diag features` with the MX Ergo connected through its Unifying receiver, replacing the missing diagnostic output in the issue. Then compare the device's HID++ identity and feature dump with existing supported devices. Done means the MX Ergo is detected and its feasible controls, including button remapping and DPI or precision-mode handling, work through OpenLogi.

Written by the indexing model from the issue text.