feat: VM snapshots and reboot_host through the API

get_vm_snapshots, create_vm_snapshot, delete_vm_snapshot and
rollback_vm_snapshot for VMs and containers, so netOrk's snapshot view
works on Proxmox as it does on VMware. Proxmox lists the live state as a
pseudo-snapshot named "current"; it is never reported or addressable.
Containers have no RAM state, so include_memory is ignored for them.

reboot_host() restarts the node with POST /nodes/{node}/status
command=reboot instead of /sbin/reboot over SSH.

CHANGELOG.md

@@ -12,6 +12,10 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
   `suspend_vm` and `get_vm_config`. They accept a VM's name or vmid, raise
   `ValueError`/`RuntimeError` instead of returning a result dict, and wait
   for the Proxmox task to finish. `power_vm` is unchanged.
+- Snapshot methods `get_vm_snapshots`, `create_vm_snapshot`,
+  `delete_vm_snapshot`, `rollback_vm_snapshot` for VMs and containers
+  (containers never save RAM state).
+- `reboot_host()` restarts the node through the API instead of SSH.
 
 ### Changed
 - `get_vms()` reports `vmid` as a string (`"100"`), following