Expose retained runs through service API

docs/CONTAINER.md

@@ -144,4 +144,9 @@ podman run --rm -p 8080:8080 \
 
 The service layer adds in-memory job tracking and HTTP transport. Execution
 semantics remain the CLI/core semantics documented in
-`docs/LOCAL-SERVICE-API.md`.
+`docs/LOCAL-SERVICE-API.md`. Mounted run directories remain discoverable through
+the retained-run endpoints, for example:
+
+```sh
+curl -sf "http://127.0.0.1:8080/retained-runs?runs_dir=/runs" | python3 -m json.tool
+```