Surface documentation index for AI tooling and discoverability

[evnchn]

Motivation

When developers evaluate UI libraries, AI compatibility is increasingly a deciding factor — both for direct LLM-assisted development and because AI-powered search summaries (Google AI Overview, Perplexity, ChatGPT search) now heavily influence which libraries get recommended. NiceGUI already serves its full documentation as machine-readable JSON indices, but this capability was completely undiscoverable — buried as an implementation detail with no public-facing documentation.

This should have been surfaced from day one. The indices power our own site search and are ideal for RAG pipelines, MCP servers, and AI agent tooling, yet no one could find them without reading the source code.

This PR makes the documentation index a first-class, documented feature.

Implementation

New documentation section in Configuration & Deployment:

• Schema table describing the JSON structure (title, content, format, url, demo fields)
• Comparison table of the three available endpoints (sitewide_index.json ~140k tokens, search_index.json ~100k tokens, examples_index.json ~3k tokens) with entry counts, token estimates, and use cases
• Call for community contributions (MCP servers, AI agent skills, enhanced RAG implementations)

Homepage AI CTA (dark-box section between Installation and Features):

• Headline: "Or, let your AI do it"
• Copy highlighting that most LLMs already know NiceGUI, with a link to the documentation index for when that isn't enough
• "Learn more" button linking to the new documentation section

Documentation overview update:

• Added an "If you are an AI" note with a direct link to the machine-readable JSON index, so AI consumers landing on the documentation entry point can immediately find the structured data

Progress

• I chose a meaningful title that completes the sentence: "If applied, this PR will..."
• The implementation is complete.
• If this PR addresses a security issue, it has been coordinated via the security advisory process.
• Pytests have been added (or are not necessary).
• Documentation has been added (or is not necessary).

[evnchn]