AI-Declaration.md

I did something similar in the README.md of my foss repo. Unfortunately this doesn't seem to cover all of the possible granular scenarios of what is or isn't AI-assisted. For example, all of the documentation in my repo was 100% auto generated. All of the source files were at most "hint" level. The test sources were a mix of "hint" and "auto".

One singular level is too broad a stroke to paint to anyone who might care, I think.