feat(db): add ListenBrainz user-config and scrobble_queue queries

internal/db/queries/scrobble.sql

@@ -0,0 +1,73 @@
+-- name: EnqueueScrobble :execrows
+-- Idempotent: if a row exists for this play_event_id, ON CONFLICT does nothing
+-- and the affected-rows count is 0. Caller (MaybeEnqueue) doesn't treat 0 as
+-- an error.
+INSERT INTO scrobble_queue (user_id, play_event_id, status)
+VALUES ($1, $2, 'pending')
+ON CONFLICT (play_event_id) DO NOTHING;
+
+-- name: ListPendingScrobbles :many
+-- Worker pulls up to N pending rows whose next_attempt_at has passed.
+-- Joins play_events + tracks/albums/artists + users so the worker can
+-- assemble the LB Listen payload in one round-trip.
+SELECT
+    sq.id           AS queue_id,
+    sq.user_id      AS user_id,
+    sq.play_event_id AS play_event_id,
+    sq.attempts     AS attempts,
+    u.listenbrainz_token AS lb_token,
+    u.listenbrainz_enabled AS lb_enabled,
+    pe.started_at   AS started_at,
+    t.title         AS track_title,
+    t.duration_ms   AS track_duration_ms,
+    t.mbid          AS track_mbid,
+    al.title        AS album_title,
+    al.mbid         AS album_mbid,
+    ar.name         AS artist_name,
+    ar.mbid         AS artist_mbid
+FROM scrobble_queue sq
+JOIN users u       ON u.id  = sq.user_id
+JOIN play_events pe ON pe.id = sq.play_event_id
+JOIN tracks t      ON t.id  = pe.track_id
+JOIN albums al     ON al.id = t.album_id
+JOIN artists ar    ON ar.id = t.artist_id
+WHERE sq.status = 'pending'
+  AND sq.next_attempt_at <= now()
+ORDER BY sq.next_attempt_at
+LIMIT $1;
+
+-- name: MarkScrobbleSent :exec
+-- Successful submit. Delete the queue row AND stamp play_events.scrobbled_at
+-- in one statement via a CTE so partial failure is impossible.
+WITH del AS (
+    DELETE FROM scrobble_queue
+    WHERE scrobble_queue.id = $1
+    RETURNING play_event_id
+)
+UPDATE play_events
+SET scrobbled_at = now()
+WHERE play_events.id = (SELECT play_event_id FROM del);
+
+-- name: RescheduleScrobble :exec
+-- After a transient failure: increment attempts, schedule next attempt,
+-- record the error.
+UPDATE scrobble_queue
+SET attempts        = attempts + 1,
+    next_attempt_at = $2,
+    last_error      = $3
+WHERE id = $1;
+
+-- name: MarkScrobbleRetryAfter :exec
+-- After a 429: schedule next attempt per LB's Retry-After header, but do NOT
+-- increment attempts (the server told us to wait, not that we failed).
+UPDATE scrobble_queue
+SET next_attempt_at = $2
+WHERE id = $1;
+
+-- name: MarkScrobbleFailed :exec
+-- After a permanent failure (4xx, exhausted retries, auth) — mark failed
+-- and keep the row for diagnostics.
+UPDATE scrobble_queue
+SET status     = 'failed',
+    last_error = $2
+WHERE id = $1;