feat: register Silo overlay context for EditingContextResolver

Add 'Silo Origin' toolbar (Commit/Pull/Push/Info/BOM) registered with
Unavailable visibility. Register a Silo overlay via
FreeCADGui.registerEditingOverlay() that appends this toolbar to any
active editing context when the current document is Silo-tracked
(ownsDocument() returns True).

Consolidate PySide.QtCore imports.

freecad/InitGui.py

@@ -35,9 +35,20 @@ class SiloWorkbench(FreeCADGui.Workbench):
         except Exception as e:
             FreeCAD.Console.PrintWarning(f"Could not register Silo origin: {e}\n")
 
+        # Silo origin toolbar — shown as an overlay on any context when the
+        # active document is Silo-tracked.  Registered as Unavailable so
+        # EditingContextResolver controls visibility via the overlay system.
+        self.silo_toolbar_commands = [
+            "Silo_Commit",
+            "Silo_Pull",
+            "Silo_Push",
+            "Separator",
+            "Silo_Info",
+            "Silo_BOM",
+        ]
+        self.appendToolbar("Silo Origin", self.silo_toolbar_commands, "Unavailable")
+
         # Silo menu provides admin/management commands.
-        # File operations (New/Open/Save) are handled by the standard File
-        # toolbar via the origin system -- no separate Silo toolbar needed.
         self.menu_commands = [
             "Silo_Info",
             "Silo_BOM",
@@ -68,6 +79,44 @@ class SiloWorkbench(FreeCADGui.Workbench):
 FreeCADGui.addWorkbench(SiloWorkbench())
 FreeCAD.Console.PrintMessage("Silo workbench registered\n")
 
+
+# ---------------------------------------------------------------------------
+# Silo overlay context — adds "Silo Origin" toolbar to any active context
+# when the current document is Silo-tracked.
+# ---------------------------------------------------------------------------
+
+
+def _register_silo_overlay():
+    """Register the Silo overlay after the Silo workbench has initialised."""
+
+    def _silo_overlay_match():
+        """Return True if the active document is Silo-tracked."""
+        try:
+            doc = FreeCAD.ActiveDocument
+            if not doc:
+                return False
+            from silo_origin import get_silo_origin
+
+            origin = get_silo_origin()
+            return origin.ownsDocument(doc)
+        except Exception:
+            return False
+
+    try:
+        FreeCADGui.registerEditingOverlay(
+            "silo",  # overlay id
+            ["Silo Origin"],  # toolbar names to append
+            _silo_overlay_match,  # match function
+        )
+    except Exception as e:
+        FreeCAD.Console.PrintWarning(f"Silo overlay registration failed: {e}\n")
+
+
+from PySide import QtCore as _QtCore
+
+_QtCore.QTimer.singleShot(2500, _register_silo_overlay)
+
+
 # Override the Start page with Silo-aware version (must happen before
 # the C++ StartLauncher fires at ~100ms after GUI init)
 try:
@@ -92,6 +141,4 @@ def _handle_startup_urls():
             handle_kindred_url(arg)
 
 
-from PySide import QtCore
-
-QtCore.QTimer.singleShot(500, _handle_startup_urls)
+_QtCore.QTimer.singleShot(500, _handle_startup_urls)