Batch publish menus (full-replace)

Publish multiple draft menus to multiple outlets with **full-replace semantics**. For each target outlet, this endpoint: 1. Soft-deletes ALL existing live menus for the outlet 2. Creates new live menus from the selected drafts (one per draft per outlet) 3. Records publish logs **Full-replace behavior:** Publishing replaces all existing live menus for the target outlets. To keep multiple menus on an outlet, publish them together in one request. One transaction per outlet — if one outlet fails, others may still succeed.