Add a Prototype Agents.md File

AGENTSPLEASEFUCKOFF.md

Jokes aside, good compromise, gives well-intentioned people with AI agents better official guidance while still not allowing agentic code contributions outside of bug reports.

TLDR:

> SQLite does not (currently) accept agentic code. However the project will accept agentic bug reports that include a reproducible test case. Patches or pull requests demonstrating a possible fix, for documentation purposes, are welcomed.