Combine the broth, farro, herbes de Provence and ½ teaspoon of the salt in a large saucepan over high heat. Bring to a boil, reduce the heat to a simmer, cover and cook until farro is tender, about 45 to 50 minutes. Stir in the zucchini, cook 1 minute and drain. Transfer to a large bowl and add the chicken, grapes, almonds and parsley to the farro.
In a small bowl, whisk together the lemon juice, zest, mustard, olive oil, pepper and remaining salt. Pour the lemon juice mixture over the farro salad and toss. Serve warm or at room temperature.