Metrics are served on METRICS_PORT (default 2112, "off" to disable), never on
the public port. Besides the Go runtime and process metrics this adds:
- http_requests_total and http_request_duration_seconds per route pattern,
from an Echo middleware.
- musicserver_songs_requested_total and musicserver_songs_played_total by
pick mode (random, low, classic). The mode is now stored with each queued
song (migration 000006, not released yet).
- Library size, sync duration, last successful sync, broken songs from the
last full sync, and the database connection pool.
Refs #35, #36, #37
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
