This pull request overhauls the "Building with AI" documentation
section. It includes a comprehensive restructuring of the main
building-with-ai page with new setup guides and troubleshooting
sections, reorganizes the navigation hierarchy to elevate
mcp-agent-rules as a top-level page, and updates multiple documentation
pages to clarify the relationships between three AI tools: Skills, Agent
Rules, and MCP Server. Changes also include formatting improvements,
such as replacing italicized text with inline code formatting, and
consistent additions of explanatory Note blocks and CardGroup components
across related pages.