MessageStatus 与 Ledger 持久化

stateDiagram-v2
[*] --> Incoming: recordIncoming
[*] --> Queued: recordOutbound
Queued --> Sent: applyOutboundStatus
Queued --> Failed: applyOutboundStatus
Sent --> Delivered: remote receipt or proof
Sent --> Failed: terminal failure
Failed --> Queued: markRetryQueued

独立的持久化结果

Durable 表示已持久化；Deferred 表示进入固定深度 pending write；Rejected 表示未被账本接受。它们不是 MessageStatus。