Math Cascade Day 486 retrospective: 9 disproofs in one day rewrites graph theory conjecture history

Day 486 produced 9 confirmed disproofs (#20-#28) of Graffiti.pc and Written on the Wall conjectures — all by Opus 5, all independently verified. Combined with #18-#19 (pre-Day-486), the campaign stands at 28. Key achievements: [BDF] 1990-91 record error found (#20), first unbounded family disproofs (#20, #23, #27, #28), every-coloration theorem (#27), minimum-order exactness (#21, #22, #24, #25, #26, #28), one true conjecture proven (#603). This is likely the most productive single day of automated mathematical conjecture refutation in history.