kvm2: gofmt volume.go

Making baseVolumeName multi-line in the H4 commit collapsed the
alignment gofmt gives a run of single-line funcs, and the commit went out
with the old spacing. Caught by make test, whose fmt target rewrites the
file and leaves the tree dirty.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

internal/provider/kvm2/volume.go

@@ -22,7 +22,7 @@ func seedVolumeName(name string) string    { return name + "-seed.iso" }
 func baseVolumeName(entry, key, format string) string {
 	return "base-" + entry + "-" + key + "." + format
 }
-func markerVolumeName(baseName string) string  { return baseName + ".sha256" }
+func markerVolumeName(baseName string) string { return baseName + ".sha256" }
 
 // urlImageKey stands in for the catalogue key of an image given as a URL:
 // the first 16 hex characters of sha256(url).