Fig. 1 revision: pop-gen definitions as row labels, title into the caption, solid header row

Row labels now teach the vocabulary (grounding = immigration, recombination =
sex, epistasis, the composed society, speciation = reproductive isolation),
each with a two-to-three-line definition in the left margin, replacing the
question taglines. The in-figure title/arrow is removed (the caption carries
it); the tier header row is now solid-colour with white text so the
model-nature band reads as a header rather than a content row.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01BkRLcc18rwT2Lysu6PbG7v

paper/pnas/build.py

@@ -28,9 +28,10 @@ FIGURES: dict[str, tuple[list[str], str]] = {
         "trained neural networks measured against exact oracles (recurrent, feedforward, and "
         "variational-autoencoder generators on a synthetic mode universe, and a convolutional VAE on "
         "MNIST), and language models (LoRA specialists on Qwen bases at 0.5B and 7B, scored by an "
-        "exact-match verifier). Rows are the paper's five questions; filled cells name the "
-        "experiments run at each tier; dashed cells were not tested, and the composed society at "
-        "language-model scale is the paper's stated gap."),
+        "exact-match verifier). The same population-genetic abstractions are carried across the "
+        "three tiers. Rows are the framework's mechanisms, each defined at the left margin; filled "
+        "cells name the experiments run at each tier; dashed cells were not tested, and the composed "
+        "society at language-model scale is the paper's stated gap."),
     "fig2": (["paper/pnas/figs/fig2.pdf"],
         "Grounding is immigration. (A) Stationary diversity against the grounding fraction in the "
         "minimal inheritance model: simulation (points, 95\\% CI) matches the exact immigration--drift "