Add Ask AI chat widget to the documentation site

[dzuluaga]

Summary

Add an AI-powered chat widget to the Multipaz developer website that lets users ask questions and get instant answers based on our documentation.

Motivation

Developers exploring Multipaz often need to navigate across multiple docs pages to find answers. An AI assistant embedded directly in the site can help them get started faster, find relevant guides, and understand concepts without leaving the page.

Dependencies

• Set up Gemini API key for Ask AI widget #53
• Set up hosting environment for Ask AI backend #54

Implementation

PR: #51

Frontend

• Floating chat widget with a sparkle FAB button
• Markdown rendering with syntax highlighting
• Session persistence across page navigation
• Suggested starter questions and follow-up suggestions
• Dark mode support
• Experimental feature banner with link to report issues

Backend

• Gemini 2.5 Flash model with full docs context (free tier)
• Vercel serverless function for production deployment (free tier)
• Dockerfile for alternative container deployment
• Per-IP rate limiting
• RAG context built from local docs, codelabs, blog, and the multipaz repo

Demo

https://dzuluaga.github.io/multipaz-developer-website/