- Implement check_updates with full update information
- Implement list_updates and get_update_status
- Implement refresh_updates and install_updates
- Implement get_update_history
- All operations use proper error handling with Option safety
- Add 2 unit tests for update info and status serialization
- Add proxmox module with client, cluster, and resource management
- Implement VM management stubs with full API documentation
- Add database migrations for proxmox_clusters and proxmox_resources tables
- Implement IPC commands for cluster CRUD operations
- Add Proxmox state management to AppState
- Create 22 unit tests for Proxmox modules (all passing)
- Update lib.rs, state.rs, and integrations.rs for Proxmox integration
