Introduces the Entry and Attachment types that the storage plugin will use as the source of truth for named storage volumes, replacing the colon-delimited mount strings stored under docker-options. Entries persist as JSON under config/storage/entries and validate against scheduler-specific rules; attachments persist via the property list and capture how an app uses an entry. The legacy migration name synthesizer is also added so existing colon-form mounts can converge on a deterministic legacy- entry name. Existing storage commands are unchanged in this commit.
