- Fix SSE listener URL: _listen() used '/api/events' but _get_api_url()
already returns a URL ending in '/api', producing '/api/api/events'.
Changed to '/events' to match _test_sse().
- Replace all Command.get().Activated() calls in silo_origin.py with
FreeCADGui.runCommand(). The C++ Gui::Command wrapper returned by
Command.get() does not expose .Activated() to Python.