Fix Qt6 StandardButton TypeError and C++ ViewProvider Proxy errors

Three fixes:

1. Remove int() wrapper from getStandardButtons() return values.
   In Qt6/PySide6, the | operator on QDialogButtonBox.StandardButton
   returns a StandardButton enum that is not convertible to int via
   int(). FreeCAD's task panel system accepts the enum directly.
   Affected files: datum_commands.py, datum_viewprovider.py,
   assembly_pattern_commands.py

2. Guard _setup_ztools_viewprovider() against C++ ViewProviders.
   PartDesign datum objects (Plane, Line, Point) use pure C++
   ViewProviders (e.g. ViewProviderDatumPlane) that don't expose a
   Proxy attribute. The previous code crashed with:
   'Gui.ViewProviderGeometryObject' object has no attribute 'Proxy'
   Now checks hasattr(vo, 'Proxy') before attempting assignment and
   wraps the assignment in try/except as a secondary guard.

3. Use persistent setPropertyStatus('Hidden') instead of transient
   setEditorMode(2) for hiding attachment properties (MapMode,
   Support, etc.). setEditorMode is session-only and resets on
   document reload, leaving 'MapMode: Deactivated' visible in the
   property panel. setPropertyStatus persists in the document file.

ztools/ztools/commands/assembly_pattern_commands.py

@@ -339,7 +339,7 @@ class AssemblyLinearPatternTaskPanel:
         return None
 
     def getStandardButtons(self):
-        return int(QtGui.QDialogButtonBox.Ok | QtGui.QDialogButtonBox.Cancel)
+        return QtGui.QDialogButtonBox.Ok | QtGui.QDialogButtonBox.Cancel
 
 
 class AssemblyLinearPatternCommand:
@@ -758,7 +758,7 @@ class AssemblyPolarPatternTaskPanel:
         return None
 
     def getStandardButtons(self):
-        return int(QtGui.QDialogButtonBox.Ok | QtGui.QDialogButtonBox.Cancel)
+        return QtGui.QDialogButtonBox.Ok | QtGui.QDialogButtonBox.Cancel
 
 
 class AssemblyPolarPatternCommand:

ztools/ztools/commands/datum_commands.py

@@ -814,7 +814,7 @@ class DatumCreatorTaskPanel:
         return True
 
     def getStandardButtons(self):
-        return int(QtGui.QDialogButtonBox.Ok | QtGui.QDialogButtonBox.Cancel)
+        return QtGui.QDialogButtonBox.Ok | QtGui.QDialogButtonBox.Cancel
 
 
 class ZTools_DatumCreator:

ztools/ztools/commands/datum_viewprovider.py

@@ -32,7 +32,7 @@ class ZToolsDatumViewProvider:
         self._hide_attachment_props(vobj)
 
     def _hide_attachment_props(self, vobj):
-        """Hide FreeCAD attachment properties."""
+        """Hide FreeCAD attachment properties using persistent property status."""
         if not vobj or not vobj.Object:
             return
 
@@ -48,7 +48,7 @@ class ZToolsDatumViewProvider:
         for prop in attachment_props:
             try:
                 if hasattr(obj, prop):
-                    vobj.setEditorMode(prop, 2)  # 2 = Hidden
+                    obj.setPropertyStatus(prop, "Hidden")
             except Exception:
                 pass
 
@@ -402,4 +402,4 @@ class DatumEditTaskPanel:
 
     def getStandardButtons(self):
         """Return dialog buttons."""
-        return int(QtGui.QDialogButtonBox.Ok | QtGui.QDialogButtonBox.Cancel)
+        return QtGui.QDialogButtonBox.Ok | QtGui.QDialogButtonBox.Cancel

ztools/ztools/datums/core.py

@@ -71,17 +71,9 @@ def _hide_attachment_properties(obj):
     Hide FreeCAD's vanilla attachment properties from the property editor.
     This prevents user confusion since ZTools uses its own attachment system.
 
-    Editor modes:
-        0 = Normal (visible, editable)
-        1 = Read-only
-        2 = Hidden
+    Uses setPropertyStatus with "Hidden" which persists across save/restore,
+    unlike setEditorMode which is transient.
     """
-    if not hasattr(obj, "ViewObject") or obj.ViewObject is None:
-        return
-
-    vo = obj.ViewObject
-
-    # Hide attachment-related properties
     attachment_props = [
         "MapMode",
         "MapPathParameter",
@@ -93,7 +85,7 @@ def _hide_attachment_properties(obj):
     for prop in attachment_props:
         try:
             if hasattr(obj, prop):
-                vo.setEditorMode(prop, 2)  # 2 = Hidden
+                obj.setPropertyStatus(prop, "Hidden")
         except Exception:
             pass  # Property might not exist on all datum types
 
@@ -102,21 +94,33 @@ def _setup_ztools_viewprovider(obj):
     """
     Set up a custom ViewProvider proxy for ZTools datums.
     This enables custom double-click behavior to open ZTools editor.
+
+    Note: PartDesign datum ViewProviders (e.g. ViewProviderDatumPlane) are
+    pure C++ and do not support Python proxies. In that case we skip the
+    custom ViewProvider setup — the datum still works, just without custom
+    double-click edit behavior.
     """
     if not hasattr(obj, "ViewObject") or obj.ViewObject is None:
         return
 
     vo = obj.ViewObject
 
+    # C++ ViewProviders for PartDesign datums don't expose a Proxy attribute
+    if not hasattr(vo, "Proxy"):
+        return
+
     # Only set up if not already a ZTools ViewProvider
-    if hasattr(vo, "Proxy") and vo.Proxy is not None:
+    if vo.Proxy is not None:
         if hasattr(vo.Proxy, "_is_ztools"):
             return
 
     # Import here to avoid circular imports
     from ztools.commands.datum_viewprovider import ZToolsDatumViewProvider
 
-    ZToolsDatumViewProvider(vo)
+    try:
+        ZToolsDatumViewProvider(vo)
+    except Exception:
+        pass  # C++ ViewProvider doesn't support Python proxy assignment
 
 
 def _setup_ztools_datum(