feat: Admin is a left rail with how many wait on you in each queue, and the Overview opens with a verdict, the queues that need you and since when, then the clear ones on one line (M503 #5605)

- GET /api/admin/summary: every admin queue (requests, reported tracks,
  playback errors, duplicates, suspect sources, missing files) with its
  count and the age of its oldest item, in one query.
- The admin layout drops the 11-tab strip for SectionRail, as Settings and
  the Collection have, with each queue's count as its badge; the counts
  refresh on each admin navigation and every 30s.
- The Overview leads with "Nothing needs you." or "N things need you.",
  lists each waiting queue with "oldest 3d ago" and a link to it, counts a
  failed library scan as a problem, and names the empty queues on one line.
  The request and quarantine previews and the stat tiles are gone; those
  queues are worked on their own pages. A failed summary says so with Try
  again instead of reading as all-clear.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

internal/db/dbq/admin_summary.sql.go

@@ -0,0 +1,72 @@
+// Code generated by sqlc. DO NOT EDIT.
+// versions:
+//   sqlc v1.31.1
+// source: admin_summary.sql
+
+package dbq
+
+import (
+	"context"
+
+	"github.com/jackc/pgx/v5/pgtype"
+)
+
+const adminSummary = `-- name: AdminSummary :one
+SELECT
+    (SELECT count(*) FROM requests WHERE status = 'pending')::bigint                AS requests,
+    (SELECT min(requested_at) FROM requests WHERE status = 'pending')::timestamptz  AS requests_since,
+    (SELECT count(DISTINCT track_id) FROM lidarr_quarantine)::bigint                AS quarantined,
+    (SELECT min(created_at) FROM lidarr_quarantine)::timestamptz                    AS quarantined_since,
+    (SELECT count(*) FROM playback_errors WHERE resolved_at IS NULL)::bigint        AS playback_errors,
+    (SELECT min(occurred_at) FROM playback_errors WHERE resolved_at IS NULL)::timestamptz AS playback_errors_since,
+    (SELECT count(*) FROM duplicate_groups g
+      WHERE g.status = 'pending'
+        AND (SELECT count(*) FROM duplicate_group_members m WHERE m.group_id = g.id) >= 2)::bigint AS duplicates,
+    (SELECT min(g.detected_at) FROM duplicate_groups g
+      WHERE g.status = 'pending'
+        AND (SELECT count(*) FROM duplicate_group_members m WHERE m.group_id = g.id) >= 2)::timestamptz AS duplicates_since,
+    (SELECT count(*) FROM tracks WHERE source_verdict = 'suspect' AND missing_since IS NULL)::bigint AS suspect,
+    (SELECT min(source_verdict_at) FROM tracks WHERE source_verdict = 'suspect' AND missing_since IS NULL)::timestamptz AS suspect_since,
+    (SELECT count(*) FROM tracks WHERE missing_since IS NOT NULL)::bigint           AS missing,
+    (SELECT min(missing_since) FROM tracks WHERE missing_since IS NOT NULL)::timestamptz AS missing_since
+`
+
+type AdminSummaryRow struct {
+	Requests            int64
+	RequestsSince       pgtype.Timestamptz
+	Quarantined         int64
+	QuarantinedSince    pgtype.Timestamptz
+	PlaybackErrors      int64
+	PlaybackErrorsSince pgtype.Timestamptz
+	Duplicates          int64
+	DuplicatesSince     pgtype.Timestamptz
+	Suspect             int64
+	SuspectSince        pgtype.Timestamptz
+	Missing             int64
+	MissingSince        pgtype.Timestamptz
+}
+
+// What the admin rail and the Overview's verdict read (#5605): each queue
+// that waits on a person, with how many and since when. One round trip, so
+// the rail costs one cheap read on every admin page. The "since" is the
+// oldest item still waiting: how long the queue has been left, which is what
+// tells the operator a count of 2 is fine today and wrong after a month.
+func (q *Queries) AdminSummary(ctx context.Context) (AdminSummaryRow, error) {
+	row := q.db.QueryRow(ctx, adminSummary)
+	var i AdminSummaryRow
+	err := row.Scan(
+		&i.Requests,
+		&i.RequestsSince,
+		&i.Quarantined,
+		&i.QuarantinedSince,
+		&i.PlaybackErrors,
+		&i.PlaybackErrorsSince,
+		&i.Duplicates,
+		&i.DuplicatesSince,
+		&i.Suspect,
+		&i.SuspectSince,
+		&i.Missing,
+		&i.MissingSince,
+	)
+	return i, err
+}