Admin: leases, pin, release, drain, usage, metrics

cmd/crossbar/main.go calls admin.Handler with the new 6-arg signature, passing nil for the not-yet-wired leases/limiter/store/drainer (task 07 wires them) so go vet and go test ./... pass on cmd/crossbar. This is a compile fix, not the task-07 wiring; noted in the implementer-log.

Implemented-By: OpenCode session (model recorded in docs/implementer-log.md)

internal/store/store.go

@@ -95,6 +95,14 @@ func (u UsageRow) CacheHitRatio() float64 {
 	return float64(u.CachedTokens) / float64(u.PromptTokens)
 }
 
+// StatusCount is one (route, host, status) group of live requests, for the metrics endpoint, which
+// needs the per-status breakdown Usage cannot give.
+type StatusCount struct {
+	Route, Host string
+	Status      int
+	Count       int64
+}
+
 // Store holds the SQLite connection to crossbar's durable state.
 type Store struct {
 	db *sql.DB
@@ -232,6 +240,23 @@ func (s *Store) Usage(since time.Time, by By) ([]UsageRow, error) {
 	return scanUsage(rows)
 }
 
+// StatusCounts groups the live requests at or after since by (route, host, status). It reads the
+// requests table only; the rolled-up requests_daily rows are not in it (Prune has moved them out of
+// requests), so counts cover only traffic still in the live table.
+func (s *Store) StatusCounts(since time.Time) ([]StatusCount, error) {
+	sinceMs := since.UnixMilli()
+	rows, err := s.db.Query(`
+		SELECT route, host, status, COUNT(*)
+		FROM requests WHERE started >= ?
+		GROUP BY route, host, status
+		ORDER BY route, host, status`, sinceMs)
+	if err != nil {
+		return nil, wrap(err)
+	}
+	defer rows.Close()
+	return scanStatusCounts(rows)
+}
+
 // Events returns lease events at or after since, oldest first, at most limit.
 func (s *Store) Events(since time.Time, limit int) ([]LeaseEvent, error) {
 	rows, err := s.db.Query(`