Establishes contributor guidelines based on maintainer team discussion.
VISION.md defines project identity, principles, and explicit rejection
criteria. CONTRIBUTING.md covers assign-then-PR workflow, RFC process
for architectural changes, AI disclosure policy, and testing standards.
PR template restructured around TL;DR + What/Why/How format.
Co-authored-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
