fix: use Properties initializer for InputSchema in IChatClient extensions#83

sd-st merged 3 commits intoanthropics:nextanthropics/anthropic-sdk-csharp:nextfrom

mattbrailsford:fix/ichatclient-inputschema-propertiesmattbrailsford/anthropic-sdk-csharp:fix/ichatclient-inputschema-propertiesCopy head branch name to clipboard