[plan] Add inline definitions for domain-specific terms throughout documentation

[github-actions]

Objective

Add inline definitions or tooltips for domain-specific jargon on first use to reduce cognitive load and context-switching for beginners.

Context

Beginner testing revealed that users must frequently navigate to reference documentation to understand basic concepts like "frontmatter", "MCP", "safe-inputs", "safe-outputs", "engine", and "toolsets".

Terms to Define

Add brief inline definitions for these terms on first use:

1. Frontmatter - The YAML metadata section at the top of workflow files
2. MCP - Model Context Protocol (expand acronym, explain it's for AI tool integration)
3. Safe-inputs - Validated user input to prevent injection attacks
4. Safe-outputs - Validated GitHub API operations
5. Engine - The AI model/provider (Copilot, Claude, etc.)
6. Toolsets - Collections of capabilities provided to the AI agent

Approach

For each term, add a brief parenthetical definition on first use:

The frontmatter (YAML metadata section) contains configuration...
Configure the MCP (Model Context Protocol) server for tool integration...
Safe-inputs (validated user input) prevent injection attacks...

Files to Update

Search for first use of each term in:

• docs/src/content/docs/guides/quick-start.md
• docs/src/content/docs/guides/agentic-authoring.mdx
• docs/src/content/docs/examples/*.md
• Other getting-started pages

Acceptance Criteria

• Each term has an inline definition on first use
• Definitions are concise (under 10 words)
• Links to full glossary entries remain for deeper explanation
• Beginners can understand concepts without leaving the page

AI generated by Plan Command for discussion #7874