[Lume] VM Snapshot Management

Current Behavior

Currently lume does not support creating, managing, or restoring VM snapshots.

Desired Behavior

Ability to:

• Create named snapshots of running or stopped VMs
• List available snapshots for a VM
• Restore VMs to previous snapshots
• Delete snapshots
• Export/Import snapshots

Technical Implementation

macOS Virtualization.Framework already provides snapshot support through VZMacOSVirtualMachineSnapshot class, which offers:

• VZMacOSVirtualMachine.takeSnapshot() - Creates a snapshot of the current VM state
• VZMacOSVirtualMachine.restoreSnapshot(_:) - Restores VM to a previous snapshot
• Snapshot data can be written to disk using write(toFile:) and loaded using init(contentsOf:)

This native support makes implementation straightforward, mainly requiring:

1. CLI interface to expose snapshot functions
2. Snapshot management system
3. Storage handling for snapshot files

Proposed CLI Commands

# Create snapshot
lume snapshot create <vm-name> [--name <snapshot-name>]

# List snapshots
lume snapshot list <vm-name>

# Restore snapshot
lume snapshot restore <vm-name> <snapshot-name>

# Delete snapshot
lume snapshot delete <vm-name> <snapshot-name>

# Export snapshot
lume snapshot export <vm-name> <snapshot-name> <output-path>

# Import snapshot
lume snapshot import <vm-name> <snapshot-path>