Preheat the oven to 350° and position 2 racks in the lower third. In a large bowl, using an electric mixer, beat the butter and brown sugar until fluffy. In a small bowl, dissolve the baking soda in the warm water, then beat it into the butter mixture. Add the eggs, vanilla and orange zest and beat at low speed until combined. Beat in the flour and salt until barely combined, then mix in the oats, cranberries and chips.