Copy AssistBot?

Build me a Customer Support web app like AssistBot.

AssistBot does: AssistBot is an AI chatbot that learns from your docs, PDFs, and website. Answers customer questions instantly, books meetings from chat, triggers human handoff when needed, and connects to your APIs  It reportedly makes about $49/mo, so the core idea clearly has demand — I want a lean version I can run and charge for.

Start from the open-source project iOfficeAI/AionUi (https://github.com/iOfficeAI/AionUi) — reuse what fits, strip its branding, and build the specifics below on top of it.

Requirements:
- A chat UI (streaming responses) wired to an LLM with a system prompt you can edit.
- Knowledge base: upload docs/URLs, embed them, and answer from that context (RAG).
- Multi-conversation history, saved prompts, and a shareable/embeddable widget.
- Usage limits per plan and an admin view of conversations.

Also:
- Clean, modern, responsive UI with a thoughtful landing page.
- Email/password auth and a simple paid tier (Stripe test mode) so it's ready to charge.
- A README covering setup, environment variables, and how to deploy.

Ship a working MVP I can run locally first, then help me deploy it.