Apple Silicon Scaleway recycles reuse the local Golden cache instead of re-pulling the VM image

Faster Apple Silicon Scaleway VM provisioning on recycle. Previously, the warm-path probe for the cached Golden VM image re-pulled the multi-GB image from the OCI registry on every single recycle, even though the image was sitting on disk. This happened because tart get returns the VM Size field as a quoted decimal string, but the Go code only accepted integers, so json.Unmarshal errored out and ensureGolden treated the cached golden as absent. The fix makes the warm-path probe correctly recognize the on-disk golden, so recycles now clone from it locally (APFS clonefile, no network) instead of re-pulling. Expect provision delay on a cached host to drop from minutes to seconds, with the per-host golden now actually reused.