Validation: #19 Add /metrics endpoint with Prometheus metrics gem
Result
PASS — /metrics endpoint merged via PR #47 (squash). yabeda-rails 0.11.0, yabeda-prometheus 0.9.1, yabeda-puma-plugin 0.9.0. Route mounted, Puma plugin activated, lograge suppression in production. 3 request specs added (200 status, text/plain content type, not HTML error page). solid_cable 3→4 bump confirmed harmless (not configured).
Evidence
- PR #47 merged with 3 commits squashed
- spec/requests/metrics_spec.rb — 3 examples
- 89 total specs passing (86 + 3 new)
- QA review: APPROVED with 4 nits, no blockers