chore(gates): export-preset-axis asset sheet against the raised reference set

Adds the RadioMast.Unity selector to scripts/asset_sheet.py and regenerates
the asset sheet and contact sheet after rebasing onto the new reference set
(#257) and the new bmesh-gear calibration hero (#258).

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
Signed-off-by: TMHSDigital <154358121+TMHSDigital@users.noreply.github.com>

Author: TMHSDigital

docs/gallery/asset-sheets/export-preset-axis.webp

@@ -65,6 +65,7 @@
     "grain-sacks": (r"^SacksLow$", None),
     "rope-bridge": (r"^BridgeLow$", None),
     "wheelbarrow": (r"^BarrowLow$", None),
+    "export-preset-axis": (r"^RadioMast\.Unity$", None),
 }
 
 _REF_LINE = re.compile(r"Asset-sheet gate.*?reference set — currently (.+?) — rendered", re.S)