Delete docs/AUTO_TYPE_FINDINGS.md

The auto-tensor-type design notes now live in docs/quantization_and_gguf.md.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_011Lu4YuXcqKJL6Yvi86ybUW

Author: pwilkin