docs(library): update what-is-an-ai-agent-definition-how-it-works-and-examples - #9008

Summary

• Refreshes the library post what-is-an-ai-agent-definition-how-it-works-and-examples (apps/sim/content/library/what-is-an-ai-agent-definition-how-it-works-and-examples/index.mdx).
• Title unchanged.
• A replacement article was merged into the existing post.
• Requested change: MERGE this additive comparison module into the existing library post at library/what-is-an-ai-agent-definition-how-it-works-and-examples; do not replace or rewrite the existing article wholesale. Keep the existing title and preserve every existing FAQ question verbatim unless factually wrong, every …

Generated by the Library Post PR Updater workflow. Not built or tested locally. After the PR opens, the workflow content gate checks changed paths, frontmatter keys, FAQ placement, and internal links; CI check:library-content validates the post once it is enabled.

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