common.rs held the wire messages, what a node sends and when, and what
a remote scan's caller tracks. Each now has its own module:
- message: CustomMessage and Metrics, the protocol between nodes.
- node_messages: NodeMessages, NodeRole and MetricsInfo, the sending side.
- remote_scan: RemoteScanMetrics, RemoteScanState and NodeProfiles, the
receiving side.
FlightMessage, the decoder's output, moves into decoder. Code moves
without changes; callers import from the new modules.
haohuaijin
33e173e5f5