Make the README demo easier to understand for first-time visitors.
Acceptance criteria:
- Add a short transcript or bullet walkthrough for the linked demo video.
- Add captions for assets/rust_terminal.png and any major screenshots.
- Explain what is mock/paper mode versus any external API-backed mode.
- Keep the first-screen README concise.
Make the README demo easier to understand for first-time visitors.
Acceptance criteria: