chore: purge force-committed simulated datasets [#151]

pre_build's old `git add -f dataset/` force-committed simulated datasets against
this repo's bare `dataset/` gitignore. Every example/tutorial self-provisions via
`if not dataset_path.exists(): subprocess.run([sys.executable, simulator])`, so the
data regenerates at runtime — nothing is lost. Recoverable via pre-purge SHA;
condemned via PyAutoGut.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_016CFXggMj2qQz31hWfh1R8M

Author: 2 people