Show expected vs actual pace/HR per lap in the Review Queue

Activities recorded from a structured Garmin workout carry a workoutId;
when its steps line up 1:1 with the recorded laps, the per-step target
pace/HR zone is resolved (via a Karvonen lookup for named zones) and stored
on each lap. The Review Queue plots it against the actual per-lap pace/HR
so the user can eyeball whether a run matches its plan while sorting it.

backend/internal/api/review.go

@@ -21,6 +21,7 @@ func (s *Server) handleReviewQueue(w http.ResponseWriter, r *http.Request) {
 	type item struct {
 		store.KindAssignment
 		Activity store.Activity `json:"activity"`
+		Laps     []store.Lap    `json:"laps"`
 	}
 	items := make([]item, 0, len(queue))
 	for _, a := range queue {
@@ -32,7 +33,12 @@ func (s *Server) handleReviewQueue(w http.ResponseWriter, r *http.Request) {
 		if !ok {
 			continue
 		}
-		items = append(items, item{KindAssignment: a, Activity: activity})
+		laps, err := s.DB.LapsForActivity(r.Context(), a.ActivityID)
+		if err != nil {
+			writeError(w, http.StatusInternalServerError, err.Error())
+			return
+		}
+		items = append(items, item{KindAssignment: a, Activity: activity, Laps: laps})
 	}
 
 	// Most recent run first, by when the activity actually happened (not