[FEATURE] - Additional device API endpoints.

[bitbound]

New endpoints needed.

Example Endpoint 1 (all devices, smaller payload):

IReadOnlyList<DeviceResponseShortDto> IDevicesApi.GetAllDevicesShort();

record DeviceResponseShortDto(
    string Id,
    DateTimeOffset LastSeen,
    string AgentVersion
);

Example Endpoint 2 (bulk delete):

DeleteManyDevicesResult IDevicesApi.DeleteManyDevices(IEnumerable<string> ids);

record DeleteManyDevicesResult(
    IReadOnlyList<string> SuccessIds,  // devices that existed and were successfully deleted
    IReadOnlyList<string> FailureIds   // devices that could not be deleted
);