Add configuration read/write support following the Uniview.pm pattern.
get_config() queries five ONVIF categories (DeviceInformation, DateTime,
ImagingSettings, VideoEncoderConfiguration, Profiles) via SOAP and returns
parsed XML as hashes. set_config() supports writing ImagingSettings
(Brightness/Contrast/Saturation/Sharpness/ColorSaturation) and DateTime,
treating other categories as read-only.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>