The legacy shard keeps memory storage as it is (replaced)

Proposed: the existing ledger becomes a legacy shard holding memory unchanged, while a new lean system shard takes host events, because memory storage was out of scope. NOT adopted as a lasting shape: the user lifted the memory exclusion and replaced it with MEM-DIR — memory moves onto the lean shards (U-M1). Until that transfer (MEM-3b), the legacy file keeps memory’s own appends.