fix: loss_compare caption token count (20B -> 5B)

The loss_compare.png x-axis only spans 0-5B tokens. The caption
incorrectly claimed ~20B tokens.

main.tex

@@ -302,7 +302,7 @@ Sequence length & 2,048 tokens \\
 \centering
 \includegraphics[width=0.50\linewidth]{data/loss_compare.png}
 \caption{Training loss curves: GPT-2 residual scaling vs.~Kaiming
-initialization over $\sim$20B tokens.}
+initialization over $\sim$5B tokens.}
 \label{fig:loss}
 \end{figure}
 
@@ -547,17 +547,6 @@ spread.}
 \label{fig:ckpt_weight_density}
 \end{figure}
 
-\begin{figure}[H]
-\centering
-\includegraphics[width=0.95\linewidth]{data/ckpt_weight_density_per_run.png}
-\caption{Per-checkpoint weight density breakdowns. The three checkpoints
-are \texttt{norm-15bt} (AdamW, Normal init, 15B tokens), \texttt{kami-15bt}
-(AdamW, GPT-2 residual scaling, 15B tokens), and \texttt{muon-25bt}
-(Muon, 25B tokens). Note: the iteration labels inside the figure reflect
-legacy script metadata and should be ignored in favour of the token
-budgets stated here.}
-\label{fig:ckpt_weight_density_per_run}
-\end{figure}
 
 % ======================================================================
 \section{Conclusion}