Keep a single Makefile validate-check target that prints the full
/metrics dump, highlights hit/miss fields, and curls /lancache-heartbeat.
Drop the duplicate README troubleshooting item and align the validation
chapter plus validate-config.yaml comments with that behavior.
Link: #29
The README buried hit/miss verification under the SteamPrefill validation
chapter, and advertised make validate-check without a Makefile target.
Operators need a short start → traffic → metrics path against the existing
/metrics and /lancache-heartbeat endpoints.
Link: #29