[Issue #290] UI: Drag-and-Drop Roommate Reordering in Create Form

[Ogstevyn]

In the create escrow form, roommates are added in fixed order with no way to reorder them.\n\nMake the roommate list drag-and-drop reorderable using framer-motion drag constraints. Reordering updates array order in form state.\n\nAcceptance Criteria: Dragging a roommate card reorders it in the list. Form submits in the new order.\n\nFiles: components/escrow/RoommateInput.tsx (Modify), components/escrow/CreateEscrowForm.tsx (Modify)