Update page descriptions for llms.txt and MCP servers

[sfc-gh-dmatthews]

📚 Context

In order to create a functional llms.txt, we need page descriptions. This PR adds comprehensive updates to page descriptions and keywords for SEO and LLM usage.

The Knowledge Base was not included and will be covered in another PR.

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By submitting this pull request you agree that all contributions to this project are made under the Apache 2.0 license.

[Copilot]

Pull Request Overview

This PR adds comprehensive page descriptions and keywords for SEO and LLM usage across Streamlit documentation files. The changes focus on making content more discoverable and useful for both search engines and AI tools by providing detailed descriptions and relevant keywords for each page.

• Adds description metadata to all documentation pages with detailed explanations of content
• Adds keywords metadata with relevant search terms for better SEO and discoverability
• Removes empty lines in tutorial and documentation files for cleaner formatting

Reviewed Changes

Copilot reviewed 300 out of 318 changed files in this pull request and generated 4 comments.

Show a summary per file

File	Description
Tutorials (multipage, LLMs, execution flow, elements, databases, authentication)	Added descriptions explaining tutorial content and keywords for SEO
API reference pages	Added descriptions for all API functions and keywords covering functionality
Development concepts	Added descriptions for architectural concepts, testing, configuration, and design patterns
Deployment guides	Added descriptions for deployment platforms and process guidance
Release notes	Updated descriptions to be more specific about version years

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[Copilot]

Pull Request Overview

Copilot reviewed 300 out of 318 changed files in this pull request and generated 1 comment.

Comments suppressed due to low confidence (1)

content/develop/api-reference/charts/bokeh_chart.md:1

• The deprecated text references 'streamlit-pdf' but should reference 'streamlit-bokeh' since this is about the bokeh chart component.

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