- Point enough crate at repo root README (readme = "../../README.md")
- Delete duplicate crates/enough/README.md
- Replace root README with current guidance (impl Stop + 'static,
  StopToken internally, may_stop().then_some() without almost-enough)
- Rewrite TRADEOFFS.md with everything learned:
  - Option<Arc> optimization in StopToken
  - Zero-cost Stopper→StopToken via From (flattened Arc)
  - StopToken faster than generic for Stopper (-25%)
  - impl Stop inlining advantage negligible
  - Clone not on Stop (kills dyn), 'static not on Stop (kills StopRef)
  - Cache firewall impact on benchmarks
  - Future direction for StopToken → enough migration