Guide reproduce-paper toward visual reports

[rehaanahmad2013]

Summary

• add concise visual-report guidance to the built-in /reproduce-paper skill
• require the strongest result figure immediately after the title
• emphasize implementation-led explanation, visual rhythm, honest evidence boundaries, and self-contained images
• add regression assertions for the durable report requirements

Validation

• cargo test (172 passed, 1 ignored)
• cargo fmt --check
• git diff --check