Build an AI customer support bot for WhatsApp Business. Features: 1) A welcome and opt-in flow that complies with WhatsApp messaging policies, including a clear unsubscribe command. 2) A knowledge base uploader where the owner adds FAQs, policies, and product docs, with answers grounded in those sources and no-scope detection that avoids inventing answers. 3) Quick-reply menus for the top asks: business hours, order status link, returns policy, and talk to a human. 4) A human handoff queue where any thread the bot cannot resolve is routed to an agent dashboard with full conversation context. 5) Off-hours auto-replies with the reopen time and a ticket number. 6) Conversation logging with sentiment tags, resolution flags, and common unanswered question reports. 7) Webhook integration for delivery status and incoming message events. 8) A metrics dashboard for thread volume, self-served versus escalated conversations, and average response time.