Raft::StatusSource

The read-only surface a status/metrics endpoint needs from a node. T-free by construction — every method here is independent of the state-machine command type, which lets HTTP::StatusHandler be a concrete (non-generic) class.

Included by Raft::Node(T). The threading contract still applies: these read mutable node state without locks, so callers outside the node's owning fiber must arrange their own safety (e.g. run the HTTP server in the same execution context).