fix: prevent QThread crash and Unknown command warnings on startup

InitGui.py: Store SiloAuthDockWidget reference on the QDockWidget to
prevent Python from garbage-collecting it while its 30-second QTimer is
still running. The lost reference caused 'QThread: Destroyed while
thread is still running' followed by abort.

ztools InitGui.py: Move addWorkbenchManipulator() call from module-level
into Initialize(), after command modules are imported. The manipulator
references ZTools_DatumCreator, ZTools_DatumManager, ZTools_EnhancedPocket,
and ZTools_RotatedLinearPattern, which don't exist until the imports run.

Also updates README.md and submodule pointers.

src/Mod/Create/InitGui.py

@@ -115,6 +115,8 @@ def _setup_silo_auth_panel():
         panel = QtWidgets.QDockWidget("Database Auth", mw)
         panel.setObjectName("SiloDatabaseAuth")
         panel.setWidget(auth.widget)
+        # Keep the auth object alive so its QTimer isn't destroyed while running
+        panel._auth = auth
         mw.addDockWidget(QtCore.Qt.RightDockWidgetArea, panel)
     except Exception as e:
         FreeCAD.Console.PrintLog(f"Create: Silo auth panel skipped: {e}\n")