A temporary moratorium on new development in the Stinson Beach floodplain was one result of an appeal hearing before the Marin County Board of Supervisors on Tuesday, when a decision on a proposed residential development on Calle Del Embarcadero was postponed until May. Neighbors making their second appeal before county officials argued that the project, a single-family dwelling proposed by Mill Valley realtor Heidi Hjorth, is located within a 100-year floodplain and therefore violates Local…