- Add /api/agents/host/uninstall endpoint for agent self-unregistration
- Update install.sh to notify server during --uninstall (reads agent ID from disk)
- Update install.ps1 with same logic for Windows
- Update frontend uninstall command to include URL/token flags
This ensures that when an agent is uninstalled, the host record is
immediately removed from Pulse and any linked PVE nodes have their
+Agent badge cleared.