The named-entry form of `storage:mount` had no way to set the attachment's `volume_options`, even though the legacy `host:container:opts` colon form parses options into the same field and every downstream consumer (the docker-args trigger and the storage:list/storage:report display path) already renders them. Tooling that declaratively re-applies attachments silently dropped options on every re-apply.
`SaveEntry` and `touchMigrationFlag` wrote files via `os.WriteFile` and `os.Create` and never chowned them, so the install-time legacy-mount migration produced root-owned `legacy-*.json` files in `/var/lib/dokku/data/storage-registry/entries/`. The dokku user that runs `ps:rebuild` could not read them and every rebuild on a 0.37.x to 0.38.0 upgrade failed with permission denied. The companion `repairRegistryOwnership` pass in `TriggerInstall` rewrites ownership across the whole registry tree so installs that already ran the buggy code are fixed on the next package upgrade, since the per-app migration flag would otherwise cause `MigrateLegacyMounts` to skip the broken files forever.
