feat(storage): paginate operations history with prev/next controls

Backend:
- ListStorageJobs(limit, offset) adds OFFSET for pagination
- CountStorageJobs() returns total row count for UI
- handler returns { jobs, total, limit, offset }
- JobManager.List(limit, offset) updated signature

Frontend:
- loadJobs(offset) with default 0
- Pagination UI: 'Mostrando X-Y de Z' + Anterior/Siguiente buttons
- After job start/end, reloads from offset 0
- listStorageJobs(limit, offset) API updated

Tests: fix List/ListStorageJobs calls to include offset=0

internal/web/handlers_storage.go

@@ -111,14 +111,23 @@ func (s *Server) handleStorageUpdateConfig(w http.ResponseWriter, r *http.Reques
 func (s *Server) handleStorageListJobs(w http.ResponseWriter, r *http.Request) {
 	limit, _ := strconv.Atoi(r.URL.Query().Get("limit"))
 	if limit <= 0 {
-		limit = 50
+		limit = 20
 	}
-	jobs, err := s.JM.List(limit)
+	offset, _ := strconv.Atoi(r.URL.Query().Get("offset"))
+	if offset < 0 {
+		offset = 0
+	}
+	jobs, err := s.JM.List(limit, offset)
 	if err != nil {
 		writeError(w, http.StatusInternalServerError, err.Error())
 		return
 	}
-	writeJSON(w, http.StatusOK, map[string]any{"jobs": jobs})
+	total, err := s.DB.CountStorageJobs()
+	if err != nil {
+		writeError(w, http.StatusInternalServerError, err.Error())
+		return
+	}
+	writeJSON(w, http.StatusOK, map[string]any{"jobs": jobs, "total": total, "limit": limit, "offset": offset})
 }
 
 func (s *Server) handleStorageGetJob(w http.ResponseWriter, r *http.Request) {