docs(readme): Results leads with the performance chart

The DSP / twiddle-ROM / Fmax bullets become one dark-theme bar chart
(docs/assets/results-summary.png, same data as the paper's Fig. 3,
normalized to the reference core), matching the README's other visuals.
The chart's TikZ source is committed next to it with rebuild
instructions. Bullets that don't chart — correctness, open toolchain,
license — stay.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

Author: grandchildrice

README.md

@@ -147,13 +147,17 @@ openFPGALoader -b basys3 ntt-core/build/design.bit   # LED1 = self-test PASS
 
 ## Results (measured, CI-reproducible)
 
-- **DSP** 3→1 per butterfly; the whole shipped core uses 1 DSP and 1 BRAM at
-  ~136 MHz (open flow, Artix-7 xc7a100t). The K-RED multiplier is Fmax-neutral.
-- **Twiddle ROM** −50% stored bits (ψ-fold), proven equal to the shipped table.
-- **Correctness** the own-FSM core round-trips `INTT(NTT(x))==x` and its NTT
+<p align="center">
+  <img src="docs/assets/results-summary.png" alt="FoldNTT vs the reference core, normalized to the reference (100%)" width="88%"><br/>
+  <sub><i>Open flow (yosys + openXC7 nextpnr-xilinx), Artix-7 xc7a100t. The whole
+  shipped core uses 1 DSP and 1 BRAM; the ψ-fold ROM is proven equal to the
+  shipped table at every address.</i></sub>
+</p>
+
+- **Correctness**: the own-FSM core round-trips `INTT(NTT(x))==x` and its NTT
   matches the golden reference bit-for-bit; the reference's inverse-transform
   bug (missing per-stage halving) was found by verification, reported upstream.
-- **Open toolchain** synthesis → place-and-route → bitstream with no Vivado
+- **Open toolchain**: synthesis → place-and-route → bitstream with no Vivado
   (yosys + openXC7 nextpnr-xilinx + prjxray).
 - MIT-licensed throughout (the upstream `cfntt_ref` submodule is also MIT).
 

docs/assets/results-bars.tex

@@ -0,0 +1,34 @@
+% Source for docs/assets/results-summary.png (README Results chart).
+% Rebuild:  xelatex results-bars.tex && magick -density 300 results-bars.pdf \
+%           -background '#0d1117' -flatten results-summary.png
+% Data = docs/paper/paper.md Fig. 3 (fpga/fpga_cost*.sh + fmax*.sh outputs).
+\documentclass[border=14pt]{standalone}
+\usepackage{fontspec}
+\setmainfont{DejaVu Sans}
+\usepackage{tikz}
+\definecolor{bg}{HTML}{0d1117}
+\definecolor{track}{HTML}{21262d}
+\definecolor{trackline}{HTML}{30363d}
+\definecolor{bar}{HTML}{4493f8}
+\definecolor{fg}{HTML}{e6edf3}
+\definecolor{muted}{HTML}{9198a1}
+\pagecolor{bg}
+\begin{document}
+\begin{tikzpicture}[font=\small]
+\newcommand{\perfbar}[4]{%
+  \draw[fill=track, draw=trackline] (0,#1) rectangle (6.0,#1+0.42);
+  \draw[fill=bar, draw=bar] (0,#1) rectangle (#2,#1+0.42);
+  \node[anchor=east, text=fg] at (-0.18,#1+0.21) {#3};
+  \node[anchor=west, text=muted] at (6.15,#1+0.21) {#4};}
+\node[anchor=west, text=fg, font=\small\bfseries] at (-3.4,4.55)
+  {FoldNTT streaming retrofit vs the reference core};
+\perfbar{3.05}{2.00}{DSP48 per butterfly}{33\%\; (3 $\to$ 1)}
+\perfbar{2.25}{3.00}{stored twiddle bits}{50\%}
+\perfbar{1.45}{4.76}{ENS area score}{79\%\; (969 $\to$ 769)}
+\perfbar{0.65}{5.96}{whole-core Fmax}{99\%\; ($\sim$137 $\to$ $\sim$136 MHz)}
+\draw[muted, dashed] (6.0,0.45) -- (6.0,3.70)
+  node[above, text=muted, font=\footnotesize] {reference = 100\%};
+\node[anchor=west, text=muted, font=\footnotesize] at (-3.4,0.02)
+  {lower is better for the first three bars; same function, inverse transform corrected};
+\end{tikzpicture}
+\end{document}