Widen butterfly ranges and increase grid resolution

Increase GRID to 400 for smoother fold ridges, widen X_RANGE and
C_RANGE, and reduce D_SCALE to compensate. Also mark the script
executable with a shebang.

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

butterfly_catastrophe.py

@@ -1,3 +1,4 @@
+#!/usr/bin/python3
 """
 Butterfly Catastrophe Surface — ASCII STL Generator
 
@@ -21,10 +22,10 @@ import os
 A_FIXED = -3.0
 
 # ── Tuning ──────────────────────────────────────────────────────────────────
-GRID    = 200          # grid resolution — higher = smoother ridges
-X_RANGE = (-3.0, 3.0)  # state variable x
-C_RANGE = (-1.0, 5.0)  # control parameter c
-D_SCALE = 0.5          # scale factor applied to the computed d height;
+GRID    = 400          # grid resolution — higher = smoother ridges
+X_RANGE = (-4.5, 4.5)  # state variable x
+C_RANGE = (-1.5, 7.5)  # control parameter c
+D_SCALE = 0.4          # scale factor applied to the computed d height;
                        # reduce if the model is too tall for your printer
 
 # ── 1. Height function ────────────────────────────────────────────────────────