fix: use absolute import in silo_origin.py

The freecad/ directory is not a Python package (no __init__.py) — it is
added directly to sys.path by FreeCAD. The relative import
'from .silo_commands import ...' fails when silo_origin is imported as a
top-level module, causing Silo origin registration to silently fail.

Change to absolute import 'from silo_commands import ...' to match
the import style used everywhere else in the directory.

freecad/silo_origin.py

@@ -11,8 +11,7 @@ providing the standardized origin interface.
 
 import FreeCAD
 import FreeCADGui
-
-from .silo_commands import (
+from silo_commands import (
     _client,
     _sync,
     collect_document_properties,