docs: add silent installation guide for enterprise deployments

Add comprehensive documentation covering:
- Silent install commands for Windows (NSIS, MSI), macOS (PKG, DMG), and Linux (DEB, RPM, AppImage, Snap, Flatpak)
- System and network requirements
- Post-installation configuration (servers.json, overridden-settings.json)
- Enterprise deployment scenarios (Group Policy, SCCM/Intune, MDM, Ansible)
- Installation verification commands
- Troubleshooting guide and exit codes
- Automation best practices with error handling examples

Author: jeanfbrito