silo: Fix SIGSEGV when opening assembly documents via Silo Open dialog
- Defer FreeCAD.openDocument() to after dialog.exec_() returns
ztools: Fix workbench init and spreadsheet syntax errors
- Use Gui.activateWorkbench() instead of direct Initialize() calls
- Fix syntax errors in spreadsheet_commands.py
- Auto-appends /api to base URL so users can enter just the hostname
- Loads system CA bundle for SSL verification of internal certificates
- Improved settings dialog hint text
- Create mods/ directory for Kindred Create addon modules
- Add ztools workbench as submodule at mods/ztools
- Add silo parts database as submodule at mods/silo
- Update README with new project structure and submodule instructions
