Serve a log

The confium-log-server binary (from the confium-log-server crate) exposes a growing log over HTTP: clients submit entries, fetch signed heads, and download inclusion proofs.

1. Provision the server’s signing key through the Threshold product (a threshold-signed head survives the compromise of any single operator).
2. Point monitors (confium-log-monitor) at the head endpoint; they check consistency across restarts and alert on any gap.
3. Publish the head fingerprint out-of-band (docs, release notes) so first-time clients can bootstrap trust.