A mother with a two-week-old baby struggling financially. A family forced to live in a car since December. Another displaced by a fire that tore through their complex last fall. These are some of the people that come to mind for Angela Fields as she looks on from the grassy lawn of the Calvary Episcopal Church’s annex in Flemington. In a few months, the four-family structure is slated to become Hunterdon County’s first homeless shelter for families in need. It’s still a work in progress, with construction equipment, paint canisters and fans scattered on the floor. But for Fields, the executive…