Incus: CreateCustomVolumeFromBackup nil-pointer dereference on volume_snapshots[*].expires_at (sibling-field variant of GHSA-r7w7)

Summary backend.CreateCustomVolumeFromBackup in internal/server/storage/backend.go contains an unguarded time.Time dereference on the ExpiresAt field of every volume-snapshot entry in an imported custom-volume backup. An authenticated user with cancreatestoragevolumes permission on any project ca...