Found during the v0.8.6 release review (Data Engineer persona). Deferred (>30 min) because it requires threading the resolved trace dir out of TraceConsumer.loadConfig.

After #886, altimate serve writes session traces, but the only startup output is altimate-code server listening on ... — nothing tells the operator traces are being written or where. A single startup log line (e.g. [tracing] session traces -> <dir>) would make the feature self-announcing. Needs TraceConsumer to expose the resolved exporter dir.