fix: update ROADMAP.md stale issue reference from #174 to #231

Issue #174 (Add VIN Decoder metrics instrumentation) is closed ✅.
The live-cluster verification of VIN Decoder metrics/ServiceMonitor
is now tracked by #231 (open).

Closes leeworks-agents/api-company#233

ROADMAP.md

@@ -29,7 +29,7 @@ Per-API: implement Fastify/FastAPI service matching `openapi.yaml` exactly. Rapi
 - [ ] Gatus public status page at `status.leeworks.dev` — issue #8
 - [x] Instrument every API with `api_requests_total`, `api_response_duration_seconds`, `api_data_freshness_seconds` (issue #27 — closed ✅)
 - [x] Add Prometheus metrics endpoint to holidays service (issue #180 — closed ✅)
-- [ ] Verify VIN Decoder metrics endpoint and ServiceMonitor scrape config — issue #174
+- [ ] Verify VIN Decoder metrics endpoint and ServiceMonitor scrape config — issue #231
 - [x] VIN Decoder metrics instrumentation + Grafana dashboard (issue #129 — closed ✅)
 - [x] VIN Decoder Gatus health check (issue #134 — closed ✅)
 - [x] Enable Alertmanager in kube-prometheus-stack + configure Slack receiver for SLO alerts (issue #210 — closed ✅)