chore: add graph explorer make target

README.md

@@ -81,7 +81,22 @@ See `docs/ecosystem-registry-service.md` for the standards comparison and
 service direction for registering repos and interacting with the combined
 ecosystem model. See `docs/registry-api.md` for the current registry HTTP API.
 
-Start the first registry service slice with:
+List available Make targets from the repo root:
+
+```bash
+make
+```
+
+Start the first registry service slice and graph explorer explicitly:
+
+```bash
+make graph-explorer
+```
+
+The target serves `http://127.0.0.1:8765/ui/graph-explorer` by default. Override
+`PORT`, `HOST`, or `REGISTRY_DB` if the local port or database path differs.
+
+Equivalent raw command:
 
 ```bash
 railiance-fabric-registry --db .railiance-fabric/registry.sqlite3 --port 8765