A summer wedding in France sounds like an easy wardrobe assignment until you start looking at the actual day. A formal celebration at a Paris hotel, an outdoor château wedding in the Loire Valley, dinner on a terrace in Provence, and an evening reception on the French Riviera can all happen in summer — but the outfit that works beautifully for one may be frustrating at another. Start with the dress code, then add four pieces of information the invitation may not tell you: Whe