Inbox Flow response bubbles

Added

• Completed WhatsApp Flow replies now expose their structured response metadata to the inbox message model.
• The inbox renders a temporary Flow completato bubble under completed Flow replies, showing the submitted party, dates, destinations, preferences, and other non-empty fields from the redacted response payload.
• The temporary bubble is gated by NEXT_PUBLIC_INBOX_FLOW_RESPONSE_BUBBLE_ENABLED; set it to false to hide the bubble without disabling Flow capture or journey processing.

Changed

• Flow reply persistence keeps redacted response data on the inbound message payload as well as in the canonical whatsapp_flow_events event store so operators can triage submissions directly from the conversation thread.